Material Information

Currais, Jorge L.
Place of Publication:
Gainesville, Fla.
Jorge L. Currais
Publication Date:

Record Information

Source Institution:
University of Florida
Holding Location:
University of Florida
Rights Management:
All rights reserved by the source institution.

Full Text


by Peter Matthews

The suspended ceiling is by now an all-too-familiar commonplace of modern building technique; yet,
though it has attracted much mechanical ingenuity, it has attracted rather less serious visual attention.
As a first assault on this subject our author, Peter Matthews, describes the products available
for constructing the basic, opaque, unheated ceiling, or, at least, those which he was able to find at
the time of going to press. In the September issue he will discuss lighting and heating in the ceiling.

The object of a suspended ceiling is
to reduce the height of an existing
room, to conceal unsightly or conm-
plex structure, to permit the instal-
lation of services in the space
above, or to give acoustic control.
The adjective 'acoustic' has been
iOo.wly applied by many manu-
facturers to products which absorb
sound, though it might be equally
well applied to those which reflect
sound, provided they are used as
foundd reflectors to obtain an acoustic
Wet construction of plaster on
,oame form of loathing still has its uses,
and there has been a steady develop-
ment of suspension systems for
prefabricated panel ceilings. Modular
i:ght fittings have been introduced
at lit into the panel grids and more
recentlyy a number of fully illuminated
ceiling systems have come on to tlhe
market, which together with heated
ceilings, will be dealt with in a future
.ticle. Anyone intending to select a
,isl)ended ceiling system would he
well advised to examine the '(ode
.f Practice and Manual for Light-
Weight Metal Fixing Systems' issued
by the Metal Fixing Association, :32
;~:zn Anne Street, London, WI.
.\.:liljgh only a few of the manu-
factiurrs rnane.i i.1 this article are
mie,'bers of thie Association, the best
o(i ;-,' cct.. aly maintain the

standards sct by Ithe codet ofl practice.
The various suspended ceilings
systems have been divided up into
tie following sections:
I. Jointless ceilings.
2. Modular panel ceilings.
(rt) Fibreboard.
(b) Asbestos products.
(c) Metal trays.
(rl) Plaster products.
(e) Mineral wool and cork tiles.
1. Jointless suspended ceilings
Proprietary plaster lathes may well
he the choice in cases where the shape
of a ceiling is irregular in plan.
curved in section or where no joints
are required. Whilst it is quite
possible to use ordinary expanded
metal lathing or clay lath for this
purpose, both require fixings at
relatively (lose centres which make
them rather more suitable for direct
application to the underside of
joists. 'Rilbi) t.' 'lliblath' and 'Hly-
rib' are capable of spanning in one
direction which results in a simplili-
cat ion of Ite suspension system.
Three coats of sanded plaster give
a lire rating of ialf an hour whilst
the acoustic properties will vary
according to the type of plaster
which is specified. Ordinary sanded
plasters weigh between 9 lb. and 12 lb.
per square foot per inch of thickness,
to which must be added the weight of

lathilng and supports; but if light-
weight plasters such as Carlite are
used, spans rather larger than the
maximum shown in the adjoining
table may be possible. As these
ceilingss are obviously not demount-
able, access panels must be provided
where necessary.
The cost of tlese systems is
extremely dillicult to compute
because it is substantially affected
by choice of the suspension members
which cover an extremely wide range
of possible sections and spacings.
The cost of suspension alone will
normally work out at between
14s. and :30s. per yard super; but to
this must be added the cost of plaster,
which might be expected to work
out at 7s. 2d. per yard super in the
outer London area.
2. Modular panel ceilings
There are several factors,' apart
from cost, which may influence
the choice of a prefabricated panel
suspended ceiling. Metal trays, plas-
ter and asbestos products are not
combustible but libreboard tiles are
potentially dangerous flame spreaders
unless they arc specially treated at
an extra cost of approximately
2s. Od. per square yard for plain tiles
and Os. per square yard for perforated
tiles, in order to pass at Class 1
Spread of Flame Test.

i, Diagram illustrating the terms used in this
article. Note that the word 'bearer' is used to
denote a primary member introduced to increase
the span between hangers in some of the systems.
The word 'runner' is applied to imemniers which
are in direct contact, or integral with the ceiling
itself. Some systems incorporate cross menm-
bers to strengthen the ceiling between runners.

If the object is to protect the
structure above from lire then one
of the asbestos products would be
the answer and in conditions of heavy
or intermittent condensation special
care in selection is necessary to avoid
corrosion (of metalwork) or even
failure of the ceiling panels which
might occur with some types of
plaster product. There are very few
firms who produce a suspended ceiling
which is elliciently sealed at the joints
and perhaps the best in this respect,




size of sheets

9 ft. by 2 ft., 2
other sizes would s
Ie specials i o

'ixpamet' I ft. by 2 ft. 3 in. 3
7 ft. by 2 ft. y
6 ft. by 2 ft. g
other sizes would
be specials

'Riblath' b fi. .,y ft. 3 in. 4

'Ribmet' 9 ft. by 2 ft. 0

weight maximum maximum recommended
runner spacing bearer spacing hanger spacing

1 to 3 lb. per 12 in. to 16 in. !dependent on dependent on
q. yd. depcndlent dependent on section of runners. section of
n gauge and gauge and miesh normally 2 ft. to bearers
esl 8 ft. normally up
to 8 ft.

a to 5 lb. per sq. 14 in. to 18 ii. ditto ditto 1 in,
d. dependent on dependent on n.s. t
auge and mesh gauge and mesh stlppo
or ( it
m.s. u

.33 11). per sq. yd.

J to 9- lb. per
q. yd. dependent
n gauge



2 ft.

3 ft. to 5 ft.
dependent on
width and gauge
Sof ribs




by s in i
lat will
rt 25 sq. ft.
n. diam.
od will
rt 16 sq. ft.

SCAFFOLDING OF GREAT BRITAIN LTD. The wire grid of this Dutch 15 in. centres under the lath, a procedure which seems rather complex. (Manu-
lath is linked by cloa crosses and the finished mesh must be tensioned into facturers:-N.V. Central Verkoop-en Eiiploitatiekantoor der Nederlandse
position with a special 'rake.' in. galvanized rods must then be fixed at Steengaasfabricken, Ceves, Plompetorengracht 14-16, Utrecht, Holland.)

type size sheets weight runner spacing bearer spacing hanger spacing change fre rating

clay lath 6 yds. by 1J yds. the clay crosses 18 in. 2 ft. to 8 ft. 4 ft. centres in. diam. m.s. ; hour witl normal
reduce the weight rod (galvanized) .mded plaster in
of plaster required I three coats

fire rating

J hour with normal-
sanded plAster In
tlree coats


GYPROC PRODUCTS LTD. The Plaxstele ceiling consists of plaster on The minimum thickness including bearers would be 2` in. overall.
suspended plasterboard lath and when this is backed with aluminiurm foil Based on a minimum area of 500 sq. yds. the cost of the suspension grid
and finished with Gyplite the thermal insulation is quite high (0.24 (supplied'only) is approximately 15s. sq. yd. The same area would be supplied
B.T.U./sq. ft./hr./1F). and fixed complete with plastering for approximately 38s. to 48s. per sq. yd.

type size of sheets weight asele loop channel bearers ha ormaling hangers fire rating
channel runners I hanger spacing

'Plaxstele' 3 ft. by 1 ft. 5| in. 85 lb. per sq. yd. 18 in. centres 3 ft. centres 5 ft. centres m.s. flats 1 hr. plastered with
by j in. i complete with with reinforcing Paristone 2 hrs.
plastered finish rods at 18 in. I plastered with
centres in the Gyplite
opposite direction


type size of sheets weight maximum maximum recommendedger
runner spacing bearer spacing hanger spacing hangers fire rating

24 G ly-rib 6 0 ft. to 13 ft. (in approx. 90 lb. integral ribs 11 in. 11 in. by I in. at 5 ft. centres I m.s. straps or rods retarded hemi-
I 1 ft. increments) per sq. yd. incl. deep at 31 in. 5 ft. centres hydrate gypsum
by 10i in. Hy-rib, steel centres plaster on Hy-rib
fats, hangers and (code of practice
plaster CP 211 (1949)) has
given protection for
over four hours

20 G Hy-rib 0 ft. to 16 ft. (in ditto above ditto above 11 in. by I; in. at 5 ft. centres ditto ditto
1 ft. increments) 4 ft.
by 10 in. 1 in. by in. at 4 ft. centres
4 ft. centres

28 G Hy-rib 6 ft. to 9 ft. (in ditto above ditto above 1 in. by : in. at 5 ft. centres ditto :ditto
1 ft. increments) 3 ft.
by 10 in. 1 in. by in. at 4 ft. centres
^ 3 ft.
4 in. by i, in. at 3 ft. centres
3 ft. centres

Ily-rib 7 ft. 8 in. and ditto above integral ribs I in. I in. rods at 2 ft. 2 ft. centres ditto ditto
lathing 8 ft. 2 in. by deep at 4 in b in by in. at 3 ft. centres
1 ft. 6 in. centres 2 ft.
1 in. by i' in. at 4 ft. centres
2 ft.
1 in. by in. at 5 ft. centres
2 ft.

of those considered here, would be
the Cullum system, and 'Supacoust'
with joints pointed, or Asbestolux
finished with a special 'Tretol' spray.
Where services are installed above
the ceiling, demountability mny
influence tie choice, whilst the joints
will consist of visible cover strips or
chamfered edges to give a 'V' joint.
As for pattern, texture and varia-
tions of plane, there has been little
imagination at work and it is really
astonishing that there should be so
many systems available 'different if
only in minor detail.' Ingenuity for
the most part lies buried behind an
essentially familiar facade of peg
holes and chamfered edges.
Preparation of a ceiling plan is
advisable so that tile joints, edges
and lighting points may be arranged
in an orderly manner. Slight in-
accuracies in fixing make the use of

flexible conduit desirable where light-
ing positions must be precise.
Although it is perfectly possible
to use this type of ceiling where the
plan is not rectangular (and indeed
it is often done), the effect is usually
rather unfortunate.
lReverberation absorption coclli-
cients are in most cases substantiated
by tests carried out by the National
Physical Laboratory but although
some firms give a complete analysis
many confine themselves to the
absorption coefficient at 500 cycles
per second and this is therefore the
figure given throughout this article.
This figure is admittedly not enough
since it ignores the high and low
frequencies where the products vary
in performance considerably.
The diagrams which follow are all
taken through 'runners' and whilst
they are all reproduced to the same

relative scale they are only intended
as a guide to the appearance of the
joints and where possible the usual
wall trim detail. At the same time
they do give an indication of the
suspension system in one direction
only. Where it has been possible to
give approximate prices for supplying
and fixing, these are based on 500
square yards in the London area.
(a) Fibreboard tiles
Apart from considerations of flame
spread mentioned above, the sound
absorption will vary with the quality
of the tile and its surface treatment.
Painting of plain fibreboard tiles
may well kill their effectiveness in
this respect, whilst with the various
types of perforated or incised tile
care should be taken not to clog
the perforations with paint.
Though many of these systems

may be simply installed on battens
(mounted on the structural sollit)
or fixed direct, this article only deals
with fully suspended ceilings.
(b) Asbestos products for suspended
Asbestos products have the ad-
vantage that they are non-com-
bustible, dimensionally stable, and
suitable for conditions of fluctuating
humidity when they will absorb
condensation and release the moisture
to the atmosphere by re-evaporation,
under more favourable conditions.
When perforated and backed by an
absorbent pad they can absorb sound
quite effectively.
The use of the low density boards
for tire protection has become quite
common but it should be remembered
that recessed light fittings can con-
stitute a problem in this respect.
[continued on page 61


continued from page 60] 1 ':a t a tSs s

BOWATERS SALES CO. LTD. Types B.T.1, 2, and 4 are suspension Type B.T.3 uses special in. insulation board which may be
sysIters using lBn,,,tcr standard I in. insulation board and are not intended perforated to give a reverberation absorption coefficient of 0.50 for a
for sioun, libsorptlin. pitch of 512 c/s.

system weight thickness size of board hanger spacing type of joint wall trim demountable approx. cost
system board

B.T.1 9 lb. per sq. yd. in. 2 ft. by 6 ft. to 5 ft. 6 in. maxi- visible M.S. visible cover no
10 ft. num by 2 ft. cover strip in strip fixed to materials only 12s.
I i | both directions wall per sq. yd.
B.T.2 9 lb. per sq. yd. I in. 2 ft. by 6 ft. to aluminium 'T' up | visible cover visible cover no supply and fix
10 ft. to 13 ft. max. strip in both strip fixed to (excluding
Sherardizcd steel directions wall scaffolding) 19s. to
up to 12 ft. max. 21s. per sq. yd.
by 2 ft.

B.T.3 14 to 15 lb. per I in. 2 ft. by 2 ft. 11 ft. maximum secretly fixed secret M.S. no materials only 27s.
sq. yd. by 2 ft. 'V' joint angle per sq. yd.
supply and fix 35s.
| I to 40s. per sq. yv
B.T.4 9 lb. per sq. yd(. in. 2 ft. by 6 ft. to 6 ft. maximum by visible cover visible no as B.T.1 and 2
10 ft. 2 ft. strip in both aluminium
directions angle plugged
to wall

CELOTEX LTD. The 'Concealed Fixing System' is suitable for suspended are its lightness and speed of erection (the manufacturers claim a reduction
ceilings and is normally fitted with plain k in. insulation board but i in. of some 15 per cent in labour costs over most similar systems) though
perforated insulation board panels will give a reverberation absorption it is not demountable. The reverberation absorption coefficient for the J3 in.
coefficient of 0.401 at 500 c s. lies is 0.05 and for 1 in. it is 0.85 at 500 c/s. These tiles may be obtained
The main virtues of the 'II and T' system, which is quite a recent introduction, with a while 'Highlight' finish, and may also be treated against flame spread.

thickness 1
system weight boar size of board hanger spacing type of joint wall trim demountable approx. cost
systemrof board

H and T 9 to 171 lb. i in. or 12 in. by 12 in. 4 ft. centres in 'V' joint secret no standard no, access panels unfixed from 3s. Od.
per sq. yd. 1 in. 12 in. by 24 in. both directions fixin detail can be incorporated to (is. lid. per sq.
24 in. by 24 in. yd. plus tiles

concealed 9 lb. per sq. yd. I in. normally 24 in. dependent on size 'V' joint secret no standard no unfixed complete
fixing by 24 in. of 'T' runner fixing detail with tiles 18s. per
system required sq. yd.

CULLUM CHANNEL FIXING SYSTEM FOR ACOUSTI CELOTEX TILES by breathing at the joints. The prices quoted cover various sizes of
This fixing and suspension system is specifically intended for Aconsli tile and runner spacing and although they may seem rather high in
Cclote.r tiles which are grooved to take metal tongues in the cross joints; comparison with some of the other systems there is no doubt that this
when the tiles are screwed to the spring fixing plates (the screws are is a high quality design and one of the few which give a really sound
cadmium plated) an airtight ceiling results which will not be stained airtight construction together with convenient demountability.

system weight th ness size of board hanger spacing type of joint wall trim demountable approx. cost
I of board aro

channel 18 lb. or 20 lb. .J in. or 12 in. by 24 in. 5 ft. 6 in. to 6 ft. 'V' joint with standard yes 1 in., 40s. to 45s.
fixing per sq. yd. 11 in. or 24 in. by 6; in. centres by visible flush steel channel sq. yd., 1} in., 45s.
system Acousti- 24 in. tile width fixing screw in bearer to 50s. sq. yd.
Celotex each corner of plugged to both prices supply
each tile wall and fix

JOHN DALE LTD. The Demountable Fibreboard and Fibre Acoustic metal tray systems described later. The I in. tiles give a reverberation
system offered by this firm uses the same type of spring clip as the absorption ,coefficient of 0.65 at a frequency of 500 c/s.

system weight bhkn size of board hanger spacing type of joint wall trim demountable approx. cost
of board

lemount- f in. panel and ) in. or normally 4 ft. 4 ft. centres 'V' joint wall mounted yes, dimpled supply and fix in
ible fibre- frame 11I lb./ j in. by 2 ft. with (adjustable in secretly fixed channel angles stapled to London area.
goard or sq. yd. 'V' groove to length) by 2 ft. showing 1 in. the back of panels fibreboard 80s. sq.
ibre in. panel (exc. give the visible cover clip into the steel yd.
acoustic frame) 131 lb./ appearance of strip spring 'T' runners fibre acoustic 88s.
sq. yd. two 2 ft. by sq. yd.
suspension 2 ft. tiles
system extra

TENTEST FIBRE BOARD CO. LTD. Since the panels are simply screwed Acoustic tiles; j in. Perforated Asbestolux; j in. and I in. plain Asbestolux.
to the channel runners, the runner and hanger spacing may be adjusted to Jn addition this firm produces a number of other suspension systems
fruit many types and thicknesses of panel such as:- consisting of inverted 'T' runners, showing a visible cover strip in steel or
in.insulating board; I in. Rabbit Warren panels and tiles; j in., I in., and I in. aluminium and intended for thermal insulation.

weight thickness i
system weight size of board hanger spacing type of joint wall trim demountable approx. cost

I.M.F. 11 lb./sq. yd. in. 4 ft. wide 8 ft. 3 in. centres 'V' joint (heads secret timber yes, by removing 35s. per sq. yd.
adjust. complete with (0 ft. centres if of self tapping batten fixing screws supplied and fixed
.ble metal I in. insulation plastered) by 4 ft. fixing screws plugged to but depends on size
ixing) board are visible on wall of panel, etc.

HERMESEAL ACOUSTICS LTD. lernneseal Acoustics Ltd. sell prepared.
sound absorbent tiles manufactured of Swiss pressed wood-fibre. The
suspension system described is the normal one and is largely made up of
softwood battens. The rather curious board sizes given are brought about by
metric dimensions (i.e. 4 in. by 1 ft. 7- in. by 1 ft. 77 in. 24 nmm. by

50 m. by 50 cmn.). The tiles offered are of 3 main designs, 'Perforated' (bevelled
edges),'"Rilled' (bevelled or square edges), and 'Chequered' (bevelled edges).
.1 plain panel 8 ft. 2 & in. by 3ft. 11 in. by I in. is also available. The
reverberation absorption coefficient at 500 c/s is 0.50 for both Rilled and
Perforated panels and may be treated to give (lass 1 spread of flame.

weight size of board

tiles only 1 ft. 7 Jl by 1 ft.
(- in.-13i lb./sq. 7 3 in.
vd. 8 ft. 2r in. by
Sin.--7 lb. sq. yd. 1 ft. 7. in.
h in.--6 lb1. sq. yd. 8 ft. 2yr in. by
3 ft. Il in.,

hanger spacing type of joint wall trim demountable

4 ft. centres by tile square or 'V' joint secret wall yes (where tiles
widths invisibly stapled mounted batten are screwed)
Sor visibly screwed I
to runners

approx. cost
per sq. yd.

up to 111 sq. yds.
supply only tiles
(plus carriage)
W in., 28s. Od.
i in., 21s.
J- in., 31s. Od.
f in., 28s. 8d.
* in., 33s. 9d.

JACKSONS (EDGEFOLD) LTD. 'Gorilla' Holdtite is a demountable clip-
ping system and the clips could be fitted to most kinds of tile including chip-
board, fibreboard or plasterboard. On this choice will depend the visual and

physical characteristics of the ceiling. It should be pointed out that the zinc
plated clips are fitted to two sides only, the remaining two sides being
unsupported butt joints. The chosen tiles should therefore not be subject to sag.

thickness s o b I
system weight th size of board hanger spacing type of joint wall trim demountable approx. cost

'Gorilla' -- --- 4 ft. maximum by secret fixing, no special yes normal cost of
Holdtite choice of panel is very wide tile width Tiles span detail supply and fix
between 27s. Gd. to 37s. 6d.
battens with per sq. yd.
i butt joints dependent on type
Sof board

'Transite Acoustical Panels' are employ what is essentially the same
I in. by 11) in. by 11I in. perforated demountable fixing system originally
asbestos cement tiles backed with a developed in the United States (the,.
1-in. absorbent pad which are patent has expired). Once one panel
supplied and fixed by John Dale Ltd. has been removed (and this might '
(who claim a reverberation absorption call for the use of a small ice pick ,'
coefficient of approximately 0.04 at or something similar) the remaining
500 c/s.). tiles may be unclipped very easily 1K.
There are runners but no cross for access to services .(perhaps $ :.Il
members so that there are no cover even too easily; examples have been 10, Tentest. 11, Atkinon.
strips behind the cross joints. The seen which were firmly attached on
tiles are face fixed with escutcheon one side only). It is regrettable that
pins or screws through the corner a mock 'V' joint has been introduced
perforations. When screws are used in some cases to simulate two
the tiles are of course demountable. 1 ft. by 1 ft. tiles in a 2 ft. by 1 ft.
Edges may be square or chamfered, tray as this feature may strengthen
Assuming an area of at least the tile but it has none of the defini-
500 square yards the approximate tion of an actual joint; and why not
cost of supplying and fixing would a rectangular tile for a change? A,
be 37s. per square yard. These trays have been criticized 12, Gorilla Hokldte. 13, Sundeala. I .
because of unsightly corrosion which
(c) Metal trays has occurred in restaurants and the trays of one system where this argued that they are less satisfactory
All the metal tray suspended premises where there is considerable problem does not arise (but whilst from a fire resistance point of view).
ceilings which nr considered here conldenis:tion. Aliiiuiniui is iusd for they are incombustible it might be If steel trays are used it is important
[continued on page 63

ASBESTOS INSULATION BOARD Turners Asbestos C'eent Co. Ltd. edges. The thicker the board the better the fire protection so that a J in.
Supply 'Turnall' .Alsbestos Insulatlion Board which has a density of 50 lb. per thick panel backed by 1 in. of Fibreglass mat will give 2 hours fire protection.
cu.ft. (Normal asbestos cement weighs from 120 to 140 lb. per cu.ft.) It is I in., There is no special system of suspension although smivel clips may be supplied
I in. or I in. thick and is obtainable in lengths of 4 ft. to 10 ft. (in 1 ft. incre- for fixing at 12 in. centres of support.
ments) by 2 ft. or 4 ft. wide. It has quite a pleasant natural grey finish and the The cost of plain panels 2 ft. by 2 ft. (supplied only) is as follows:
I in. board with a 4 in. airspace behind will give a reverberation absorption in ... 5s. 5d. per panel in. ... 5s. 8d. per panel
coefficient of 0.15 at 500 c/s. This board is however made up into plain or 4 in. ... s. 71d. per panel
perforated 'Asbestos cement ceiling panels' of the same thicknesses and The AItkinson and Sundeala suspension systems both of which are suitable
normally 2 ft. by 2 ft. (but up to 4 ft. by 4 ft.) with plain or chamfered for use with 'Turnall' panels are detailed here.

system weight o boas size of board hanger spacing type of joint wall trim demountable approx. oelt

reinforced I in.-18 lb. per I in. or 2 ft. by 2 ft. or 2 ft. or 4 ft. by 'V' joint. Secret yes 35s. per sq. yd.
sq. yd. I in. 4 ft. by 4 ft. 4 ft. to 12 ft. Secret aluminium (assuming 12 in.
A in.-214 lb. centres aluminium '' angle plugged suspension)
per sq. yd. 'T's screwed to to wall.
(tiles and .back of panels Recessed
suspension) and cut to fit screw fixing
over main 'T' of edge
runners panels on one
side of the
room only

fixed I in.-17 lb. per i in. or ditto as above 2 ft. by 4 ft. to.'.. 'V' joint, secret no 33s. per sq. yd.
sq. yd. i in, 12 ft. centres Secretmetal aluminium (assuming 12 in.
b in.-20{ lb. clips screwed to, angle plugged suspension)
per sq. yd. rear of tiles to wall
(tiles and
suspension) '


usual system


continued from page 62]


system weight t aickess size of board hanger spacing type of joint wall trim demountable approx. cost

Sundeala 17 lb. per sq. yd. g in. 2 ft. by 2 ft. 2 ft. by up to 'V joint secret angle plugged no supply and fix 500
complete with 6 ft. fixing (metal to wall at sq. yds. 37s. per sq.
metal sections clips screwed 2 ft. centres yd. (materials only
to back of each' not normally
panel-12 per supplied)

CAPE BUILDING PRODUCTS LTD. Asbestolux is included under 'asbes- be used. These suggestions do not completely seal the ceiling but a method
tos insulation board' because its density is similar at 48 lb. per cubic foot. has been devised by Messrs. Tretol to spray a completely impervious screen
When fitted to a steel suspension system it can give up to 4 hours fire pro- over the entire surface of the ceiling (the panels being very accurately
section, and up to 2 hours fire resistance can be given when fixing to filedd. There is no doubt that this firm have been extremely enterprising
timber, or when the panels are perforated and backed with a 1 in. Rocksil in the development of Asbestolux and have even been experimenting with
Mat. Slotted panels are also available for sound absorption. sprayed low voltage heating circuits on the face of their panels, an idea
Asbestolux panels are manufactured to tolerances of + nothing -- in. borrowed from the aircraft industry for de-icing wing tips, engine cowlings,
and they may be stove enamelled or in situations which might suffer from etc. The cost of standard grade plain panels, supplied only, are identical
extreme condensation an effective porous paint such as 'Seculate' might to those quoted for Turnall Asbestos Insulation Board.
tthickness approx. cost
system weight t kno s size of board hanger spacing type of joint wall trim demountable approx. cost
of board

AS2 48 lb. per cu. 3 in. and 2 ft. by 4 ft. 2 ft. by from 6 ft. 'V' joint secret steel yes, plain panels costs vary with
Modulux ft. A in. 2 ft. by 3 ft. to 10 ft. centres secretly fixed angle plugged only quality and locality,
design Asbesto- 4 in. depending on the to wall etc., and could be
suspended lux 2 ft. by 3 ft. gauge of 'T' .anything from a
ceiling 2 ft. by 2 ft. runners or bearers good price of 25s.
8 in. per sq. yd. to a
2 ft. by 2 ft. moderate price of
1 ft. 8 in. by 3s. per sq. yd.
3 ft. 4 in. (supplied and fixed)

o make sure that they are rust when they are to marry up with
,roofed after they have been per- traditional plaster finishes.
rated and formed for this is one
possiblee reason for past failures. (e) Mineral Wool and Cork Tiles
'renger ceilings are similar in charac- The Armstrong Cork Company Ltd. ,
er to those described here but are introduced 'Travrtone' and 'Cor -'' .
mainly intended for use with heated koustic' tiles some twelve months -=- p .-.;
ceilings and will therefore be dcs- ago, although the parent company ll' o .
ribed in a future article. in the USA has bee: producing them 1111 I III I
for about twelve years. 14, Modulue (Cape Asbestos). 15, Sanacoustic.
) Both tiles have a natural texture'
) Plaster products which arises from the nature of the
Fibrous plaster has often been material and in the case of 'Traver-
sed for suspended ceilings, especially tone' gives' it good sound absorp-
'here complex shapes are involved tion qualities (reverberation ab-
uch as moulded acoustic sound sorption coefficient 0.74 at a fre-
Iflectors and has usually been of a quency of 500 c/s and extremely
special character. However, three good absorption in the high frequency
rms are considered here who all range). The cost of these tiles (supply
produce plaster suspended ceiling only) is 29s. 3d. per square yard.
anels which can be a useful feature 'Corkoustic' tiles either plain or 16, Celotex Metal Acoustic. 17, Burgess.

CELOTEX LIMITED The prototype of this firm's metal acoustic tile was fabrication. It is the only example discussed in this article which is
shown at the recent Building Exhibition and it has only just gone into equipped with a continuous dimple on all four upstands to engage with
production. The company aim to rustproof (Bonderize) the tiles after the spring 'T' bars where necessary.

system weight size of tray hanger spacing type of joint wall trim approx. cost

Incombustible 17 lb. per sq. yd. 2 ft. by 1 ft. (with dependent on choice 'V' joints (clean no special treatment 83s. per sq. yd
metal acoustic tile i dividing groove of bearer margins and distinct unfixed
(steel) | simulating 2 tiles bevels)
1 ft. by ft.)

BURGESS PRODUCTS LTD. These trays give a fire protection of 2 hours with one staved coat of chromate primer and one stoved coat of matt off white
(B.S. No. 476: 1953). The reverberation absorption coefficient is 0.00 at 500 c/s. finishing enamel. Although perforation and shaping take place after the steel
Unperforated tiles are also available to vary the sound absorption, with or sheets have been zinc coated, the stoving enamel is applied by the 'Ransburg'
without insulating pads. The trays are fitted with two 'pips and stops' on the system of electrostatic painting which is adequate protection for normal con-
two fixing edges which clip into the 'T' runners, are zinc coated and finished editions. Special finishes are obtainable where heavy condensation is expected.

system \ weight size of tray hanger spacing type of joint wall trim approx. cost

Burgess suspended 2 ft. by 1 ft. tray 3 ft. 4 in. by 1 ft. 5 ft. centres in each ,V' joint (trays are when ceiling Is on an cost of suspension
ceiling (24 gauge with 1 in. absorbent 8 in. (divided) direction (maximum) 'fabricated from per- exact module a 2 ft. deep, 7s. Od.
perforated mild pad of glass silk 2 ft. by ft.b t. 2 f. forated sheet so per. special spring "T' per sq. yd. (unfixed).
steel) 4.5 lb. (with rock lft. 6in. by ft. 6in. forations run over runner can be used Cost of tiles varies
wool 4.7 lb.) 2 ft. by 2 ft. bevelled edges and from 19s. lid. to
2 ft. by 2 ft. (divided) : upstanda) 30s. 41d. per sq. yd.
2 ft. by in. according to quan-
1 ft. by 1 ft. tity and size (un-
all tiles have 14 in. fixed)
upstand all round

/ II

JOHN DALE LTD. Sanacoustic rust-proof aluminium trays backed by absorption coefficient of approx. 0.94 at 500 c/s. Both perforated and
I in. fibreglass or mineral wool absorbent will give a reverberation plain trays are available which allow some variation in sound absorption.

system weight size of tray hanger spacing type of joint wall trim approx. cost

Sanacoustic (22 Each tray 1 lb. 2 ft. by 1 ft. (with 4 ft. centres 'V' joints (clean un- edge channel plug- 45s. 6d. per sq.
gauge half-hard approx. dividing groove perforated margins) ged to wall showing supplied and fi
aluminium) simulating 2 tiles in. on the face (area about 500
1 ft. by 1 ft.) with yd.)
1) in. upstand all

Sa 21, Gyproc Acoustic.
10, Clark and Fenn Full Suspension. a

S20. Clark and Fenn
Minimum Suspension.

18, Petradene Supaeou2t. 2 2.. .I I I, Anderson, Travertone.

PETRADENE LTD. Messrs. Petradene Ltd. produce a range of tiles that they may be sealed by pointing, and may contain some sisal chippings or
suitable for suspended ceilings and made of plaster of Paris hardened even J in. galvanized reinforcing rods when required.
by 'Superite' under the trade name of 'Supacoust,' which have a neatly The fire rating is Class I and a reverberation absorption coeficient of
'tooled' finish. Specials may be quite easily produced and although the 0.70 with glass fibre quilt backing and 0.60 with 1 in. wood wool backing is
standard tiles have regular perforations, they are also produced with obtainable at 500 c/s.
random holes. Although the table gives details of the metal suspension system the tiles may
They are dimensionally stable, absorb condensation, are possibly unique in also be fixed to timber runners and bearers with metal strap hangers.

system weight tiles size of tile hanger spacing type of joint wall trim demountable approx. cost

Supacoust 22f lb. per sq. in in. by 2' in. by M.S. 'V joint which M.S. angle yes, even when supply only tiles
yd. 2' by 1' 8" straps at 4 ft. may be pointed. plugged to pointed by natural white,
2' by 1' 0" centres. Countersunk wall removing screws 22s. Od. sq. yd.,
2' by 1' 2" screw fixing off white, 20s. 3d.
1'8" by 1' 8" sq. yd.
1' 8' by 1' 4'
2' 6'by 'R 3'

CLARK & FENN LTD. These tiles are manufactured from gypsumn, 'and 'various patterns of moulded tile under the general trade name
are non-combustible and should give a fire rating of at least half an 'Dekora.' The 'Echostop' tiles give a reverberation absorption coeficient
hour. The tiles are of three types: plain 'Rapid,' perforated 'Echostop,' of 0.82 at 500 c/s.

system I weight t es size of tile h greommened type of joint wall trim demountable approx. cost
of tile hanger spacing.

full tiles only 311 lb. in. but 2 ft. by 2 ft. 2 ft. by 4 ft. to secretly fixed aluminium yes 'Echostop,' 45s. sq
suspension per sq. yd. with 7 ft. 6 in. centres 'V' joint angle cover yd.
1 in. strip or may 'Rapid,'40s.persq.
around marry up to 'Dekora,' 45s. per
edges ': fibrous plaster sq. yd.
surround supply and fix

minimum ditto above ditto ditto above 2 ft. by 4 ft. ditto above ditto above ditto above ditto above
suspension above centres
(4 in. max. overall

GYPROC PRODUCTS LTD. This company make a point of mentioning 1 in. bitumen-bonded fibreglass will give a reverberation absorption coefficient
that 'These ceilings shall not be erected where damp conditions prevail of 0.80 at 500 c/s. This will improve to 0.85 with a 2 in. fibreglass
or where they may be subjected, either intermittently or continuously, mat. Only the first of the three systems analysed has been illustrated
to a moist, humid atmosphere.' Acoustic Gyproc (perforated) backed with in section. They all rely on timber battens as reinforcing cross members.

system weight thickness size of tile recommended type of joint wall trim demountable approx. cost
of tile hanger spacing

acoustic 26 to 28 lb. per J in. 4 ft. by 2 ft. and 2 ft. or 4 ft. aluminium visible no 85s. to 45s. per sq
suspended sq. yd. 4 ft. by 4 ft. according to size cover strip aluminium yd.
ceiling perforated of tile by 5 ft. to showing 1I in. angle plugged
plasterboard 12 ft. dependent or I in. to wall
tile on choice of
bearer section

slotted ditto as above J in. 2 ft. by 2 ft. 4 ft. by 12 ft. 'V' joint ditto above no 45s. to 55s. per sq.
acoustic with 1 in. by centres secretly fixed yd.
tile I 1f in. timber
suspended battens
ceiling fastened to
back at 10 in.
centres forming
panels4ft.by2ft. .

plain ditto as above a in. 2 ft. by 2 ft. dependent onsize 'V joit fixed, visible screw yes 85s. to 40s. per sq.
bevelled of timber runner with: ws screws and cup yd.
edge tile and channel and cup washer into
suspended bearer washers secret batten
ceiling plugged to
[continued on page 66 6

S2 a e .L,&S continued from page 64]

striated have much more modest
sound absorption characteristics (0.32
or 0.39 at 500 c/s) but have a natural
moisture resistance and are there-
fore suitable for conditions of high
humidity such as kitchens or swim-
ming pools, etc. They cost 31s. Gd.
per square yard (supply only).

An appra
article lead

(i) Cost
The chea

isal of the details in this
s to the following con-

pest types of suspended

ceiling are either in. fibre insulation
board with visible cover strips (simi-
lar in character to a factory roof
lining system) or patent lath and
plaster, both of which- under favour-
able conditions-might be expected
to cost about 21s. per square yard
but neither would be ideal where

much access was required to servi
The more expensive ceilings must
examined on their relative mel
and may well have properties wl
would justify the extra cost.
(ii) Weight
Plaster ceilings are quite

ANDERSON CONSTRUCTION CO. LTD. 'Travertone' and 'Corkous- Construction Company is detailed here. (This firm supplies and fixes
tic' tiles may be supplied grooved and back cut for suspended ceilings many of the modular tile systems described in this article in addition
and a system developed specifically for 'Travertone' by the Anderson to some of its own.)

system weight size of board recommended type of joint wall trim demountable approx. cost
hanger spacing

for 'Traver- approx. 14 lb. 1 ft. by 1 ft. and 5 ft. to 10 ft. butt or 'V' joint secret metal no 63s. per sq. yd.
tone' tiles per sq. yd. 1 ft. by 2 ft. centres by 5 ft. secretly fixed angle plugged
complete with 'Paxolin' to wall
tongues in cross

heaviest at 85 to 90 lb. per square Armstrong's 'Travertone' (0.93), Bur- this aspect is mainly of interest when classified as 'not demountable.' So
yard complete with suspension, and gess metal tray (0.80) and John the ceiling is suspended beneath an of the fully demountable tiles mil
plaster products in the modular tile Dales's 'Sanacoustic' metal tray uninsulated roof space and has, well be suitable for temporary str
range are also on the heavy side. and Demountable Fibre Acoustic therefore, only been recorded where tures such as exhibitions.
Ialf-inch fibreboard ceilings are (0.75). the material concerned is especially
likely to weigh only 9 lb. per square At low frequency (i.e. 125 cycles effective in this respect. (vii) Moisture resistance
yard complete and J-in. perforated per second) 'Travertone' again heads 'Corkoustic' cork tiles are the oi
asbestos cement tiles (Transite) might the list (0.63), although many other (v) Hanger spacing ones which have the manufacture(
be slightly lighter. products are more ellicient in the It will be noticed that wherever unqualified recommendation for ci
middle range. Clark and Fenn's there are primary and secondary editions of heavy humidity. So
(iii) Sound absorption 'Echostop' absorbs 0.50 and Gyproc structural members supporting a plasters and low density asbes
It is debatable whether it might acoustic board with a 2-in. absorbent ceiling system, the bearers can usually boards are quite good but call
have been rather more useful to give mat has a coefficient of 0.40 at the be varied to permit large or small extra treatment in severe condition
an average reverberation absorption same frequency. Many of the sound hanger spacing in one direction.
coellicient taken over the normal absorbant tiles now in use in this This could be a useful feature where (viii) Appearance
range of frequencies for general use country were manufactured in the large trunking or other large services The mineral wool and cork ti
but according to the details supplied USA well before 1930 and now that. .must be accommodated above, are the only ones which exploit 1
by the manufacturers and usually patents have expired are appearing quality of the ingredients to give
substantiated by a National Physical on the British market. (vi) Demountability interesting texture. For the rest
Laboratory report, the types of : It may not always be vital to have the modular ceilings it is largely
ceiling which give the most effective (iv) Thermal insulation universal demountability and there matter of choosing the type
sound absorption at high frequencies Many sound absorbent materials is usually a way of providing limited perforation or joint with the great
(i.e. 4,000 cycles per second) are are also good heat insulators but access in each example that has been appeal except in the case of 1
[continued on page





.... to benefit from their know-how and experience, simply write to:


S .' Tynos Works, Scotswood, Newcastle-upon-Tyne, 5.

S, Telephone: Lemington 674658


.. ; '' ' '' '



:-' uv'7Wa 9 2 continued from pa,
'Dekorn' plaster tiles. One might
have expected more adventurous
products from this eminently mould-
able material.
(ix) Size of panel
A module of 2 ft. by 2 ft. or 1 ft.
by 1 ft. is almost universal amongst
the dry constructions except where
a product is cut down from a larger
sheet such as low density asbestos
cement board or where the product
has metric dimensions such as
Hermeseal tiles.
Presumably these dimensions
started with the economic sub-
division of 8 ft. by 4 ft. sheets and
this has now forced other products
such as modular flush light fittings
and tiles cast separately (i.e. plaster
tiles) to follow the same dimensions
which must annoy the 3 ft. 4 in.
module boys. The low density
asbestos cement board can be used
up to 10 ft. by 4 ft. and even
3 ft. 4 in. by 1 ft. 8 in. though it
would need intermediate reinforce-
ment and in the very large sheet
might prove rather unmanageable.
(x) Fire
Most suspended ceiling finishes are
either naturally capable of passing
a Class I spread of flame test or can
be treated to do so. Burgess metal
trays have been tested by the Joint
Fire Research Organization and have
been proved to give effective protec-
tion to structural steelwork for a
period of 2 hours.
Plaster ceilings can give protection
for j hour and Gyproc Plaxstele up
to 2 hours. If the problem is to
protect a light weight timber struc-
ture then probably low density
asbestos cement is the answer which
can be designed to give effective
protection for up to 4 hours.

1. Jointless ceilings: Gyproc Pro-
ducts Ltd., Singlewell Road, Graves-
end, Kent; S.G.B. Ltd., Mitcham,
Surrey; The Expanded Metal Co.
Ltd., Burwood House, Caxton Street,
S.\.1; Steel Bracketing & Lathing
Ltd., 3-8 Brigstock Parade, Thornton
Heath, Surrey; The Trussed Concrete
Steel Co. Ltd., Truscon House,
Lower Marsh, S.E.I. 2 (a) Fibreboard:
Bowater Sales Co. Ltd., Building
Boards Division, Bowater House,
Stratton Street, WV.1; Celotex Ltd.,
North Circular Road, Stonebridge
Park, N.W.10; Horace W. Cullum &
Co. Ltd., 58 Highgate West Hill,
N.6; John Dale Ltd., New Southgate,
N.11; Herneseal Acoustics Ltd., 4
Park Lane, W.1. Jacksons (Edge-
fold) Ltd., 55 Duke Street, Fenton,
Stoke-on-Trent; Tentest Fibre Board
'Co. Ltd., Fiboard House, Oakleigh
Gardens, Whetstone, N.20. Universal
Metal Furring & Lathing Co. Ltd.,
175 Merton Road, S.W.19. 2 (b)
Asbestos products: John Dale Ltd.,
New Southgate, N.11; Cape Building
Products Ltd., Cowley Bridge Works,
Uxbridge, Middx.; Turners Asbestos
Cement Co. Ltd., Trafford Park,
Manchester, 17; Sundeala Board Co.,
Sunbury-on-Thamcs, Middx. 2 (c)
Metal trays: Celotex Ltd., North
Circular Road, Stonebridge Park,
N.W.10; John Dale Ltd., New South-
gate, N.11; Burgess Products Co.
Ltd., P.O. Box 11, Hinckley, Leics.
Frengcr Ceilings Ltd., 7-12 Tavistock
Square, W.C.1. 2 (d) Acoustic perfora-
ted gypsum plaster tiles:. Petradene
Ltd., 7-8 Hobart Place, ,S,W.1;
Gyproc Products Ltd., Singlewell
Road, Gravesend, Kent; Clark &
Fenn Ltd., 16 Old Town, S.V.4.

Gatwick Airport, Control Tower and
Fire Station. Architects: Yorke, Rosen-
berg & Mardall. General contractor:
Gilbert-Ash. Sub-:ontractors: Elec-
trical: T. Clarke & Co. Heating and
ventilation: Edward Deane & Beal Ltd.
Lifts: Titan Lift Co. Metal windows
to control room: Aygee Ltd. Metal
windows: Crittall Manufacturing Co.
Structural steelwork: James Austin &
Sons Ltd. Pneumatic tubes: Lamson
Engineering Co. Flooring: Semtex
Ltd. Roofing: D. Anderson & Son Ltd.
,Blinds: Tidmarsh & Sons. Sliding
doors: Hill Aldam & Co. Roller
Shutters: Haskins. Sanitary fittings:
Stitson's Sanitary Fittings Ltd.
Ironmongery: A. G. Roberts Ltd.
Balustrading, etc.: S. W. Farmer &
Son Ltd. Suspended ceilings: Tentest
Fibreboard Co. Pie-cast concrete cills:
Girlingstone. Paint: Screeton Paint-
maker Ltd.

Gatwick Airport, Terminal Building.
'General contractor: Turriff Construc-
tion Corporation Ltd. Architects:
,Yorkc, Rosenberg & Mardall. Sub-
contractors: Roofing specialists: D.
Andersor & Son. Constructional steel:
James Austin & Sons. Lifts; Bennie
Lifts Ltd. Shop and bar fittings:
Bath Cabinet Makers Ltd. Elec-
tricians: T. Clarke & Co. External
*and venetian blinds: Deans Blinds
(Putney) Ltd. Floor tiling: Decora-
tive Floors Ltd. Heating: Edward
4Deane & Beal Ltd. Asphalte tanking:
Faldo Asphalte Co. Roller shutters:
'Haskins Ltd. Water tanks: Horseley
iBridge & Thomas Piggott. DecoratitV
Glass: T. & \W. Ide Ltd. Fabril


reinforcement: Tentor 3ar C(
mission tubes and conveyors:
Engineering Co. Spec al s
ceilings: Luxfer Ltd. Terraz
Malacarp Terrazzo Co. Scc
Mills Scaffold. Metal window:
lowes Ltd. Special wall tilin
wells (Hove) Ltd. Utile z
Norbury Joinery Ltd. PI.
Pollock Bros. (London) Lt(
and wall tiling: \V. G. Patein
Suspended ceilings: Sundeals
Co. Cold room equipment:
Insulation Ltd. Plumbing: G(
Taylor & Co. (London).
windows: Aygee Ltd. Specia
tions: Unilock Ltd. General
Warner (Glass) Ltd. Kitchen
ment: Radiation Ltd.; Benl
Sons Ltd.; James Stott ,
EUK Catering Machinery Lt,
Regional Manufacturing Co.;
Steel Co. Ironmongery: Alfi
Roberts Ltd. Sanitary fitting:
sons Sanitary Fittings Ltd.
railing and balustrading: He
Engineers Ltd. Architecture
minium work: Ajaz Archit
Products Ltd. Public address
Westrex Co. Paint: Sereeton
maker Ltd.

Belgrade Theatre, Coventry. I
contractor: George Wimpey
Sub-contractors: Structural sled
Boulton & Paul Ltd. Rei:
concrete. British Reinforced Cc
Co. Piling: Simplex Concrete
Ltd. Safety curtain: Hall
Equipment Ltd. Roller shutl
Brady & Co. Wood wool
Ialcrete Precision Panels
Counterweights, paint bridge ai
platform: Gimson & Co. (Lei
Ltd. Suspended ceiling: Steel BI
ing & Lathing Ltd. Sliding wi
P. G. Allday & Co. Metal wc
and haystack lantern: Crittall
[continued on I

------- -- ---- -- --- ------ --- -------------- --------------------


by Peter Matthet

The suspended ceiling has come to us as a screen to hide the paraphernalia of the services. It u
only therefore a matter of time before the services became incorporated in the ceiling surface.
this second article the author, Peter Matthews, considers products on the market which have be
designed to provide heating or lighting through the ceiling. This article (and its predecessor in I
July issue of the AR) should be read in conjunction with Looking Up on page 161 of this isst

In the first of these two articles we
considered the straightforward sus-
pended ceilings which attempt no
more than to conceal the services
and, in some cases, to provide special
sound deadening. In this second
article we complete our survey by
listing and commenting on the an-
cillary equipment which has been
designed specifically for building into
suspended ceilings and to provide
heating and lighting. These fall into
five categories. First there are the
modular recessed lighting fittings.
As these are legion, it is unfortunately
not practicable to follow our usual
practice of listing each separate
product; instead, as we explain
below, we group them into their
main classes, discussing the charac-
teristics of each and giving an
average price figure for each standard
size. After the recessed lighting
fittings a mention is made of visible
suspended trunking systems, though
these need not be used in suspended
ceilings. Next comes the fully illu-
minated suspended ceiling, in which
the actual translucent surface has
become the ceiling: these, as they are
relatively few, can be taken product
by product. The same is true of
heated ceilings, which are of two
types. Of these we take first the
electrically-heated ceilings, in which
the heating element is actually in-
corporated in the ceiling; and leave
till last the water-heated suspended
ceilings in which the actual heat
source is remote.
Lastly there are two words of
warning. The first concerns prices.
These are approximate only, and are
not based on identical assumptions.
The use of uncorrelated prices in
this way is open to objection; but it
is not practicable to give fully com-
parable prices and it is our opinion
that it is of more use to an architect
to have some indication of cost
(with the assumptions given whenever
possible) than to have none at all.
He must in any case get his final
prices from actual estimates.
The second warning is one which
must always be made with this type
of article: namely that we have been
able to include only those products
which we have been able to find at
the time of going to press, and that
the list may well be incomplete.
Modular recessed lights
Manufacturers of lighting equip-
ment have designed recessed fittings
to fit exactly into the 2 ft. module
which seems to have emerged as a
standard ceiling panel dimension,
and although most of them claim to
have co-operated with certain specific
ceiling manufacturers, the fittings
are really standard specials and can
usually be adapted to suit other


It is therefore very difficult to
compare costs except by quotations
for a specific job, but the prices for
the standard sizes might be expected
to fall close to the following (prices
nett to user):
2 ft. 0 in. x 2 ft. 0 in.-12 fitted
2 ft. 0 in. x4 ft. 0 in.-17 wi
2 ft. O in. X ft. 0 in.-24 plastic
Prices for dished plastic diffusers
would be similar but subject to 261
per cent purchase tax.
The same fittings containing clear
glass would be appreciably cheaper,
2 ft. O in. x 2 ft. 0 in.-10
2 ft. 0 in. x 4 ft. 0 in.--13
2 ft. 0 in. x ft. 0 in.-19
However, these would also be subject
to purchase tax if the glass actually
diffused the light.
When planning a suspended ceiling
it is important to allow for the
minimum depth required for the
electrical installation, which can be
as much as 10 in, for certain tungsten
fittings, but may be as little as a in.
in the case of fluorescent fittings.,
Some 'elbow room' is nevertheless
welcomed by all concerned.
If the ceiling is intended to give
fire protection to the structure above,
it might well be advisable to consider
some other type of illumination, for
although there is no existing law
governing this matter, 0.5 per cent
of the total area is considered a
maximum without additional fire-
proofing in the USA, which would
not give a particularly,high level of
illumination. Alternatively extra fire-
roofing could, of course, be provided,
ut might prove rather costly.
One of the drawbacks of this type
of light fitting is the fact that it
tends to leave the bulk of the sur-
rounding ceiling in darkness, resulting
in glare even if the level of illumina-
tion is quite adequate where it is
required. This can be slightly offset
by the use of light coloured finishes
on the surface below, which will
reflect upwards to a certain extent.
Some of the dished diffusers project
below the ceiling surface, 1, and
although the light source is still
above ceiling level, about 2 per cent
ceiling illumination might be ob-

1,. .u, a

_.. T- ,

I, WreueAM sad Young's dished useju prdte
:. ..tfa.ew, -.'-: '

trained. Light fittings which actually
floodlighted the ceiling might over-
come this difficulty only to emphasize
inaccuracy in the ceiling itself, but in
shops it would be simple to arrange
for some lights, secreted in fitments,
to play up on to the ceiling.
Where flat glass is used for diffus-
ing, some firms leave a gap of about
J in. between the glass frame and the
frame of the fitting so that there is a
transitional strip of soft light between

2, Troughton and Young s hitting with Spot-ls
the ceiling surface and the light
source, 2.
Apart from cost, the criteria which
may influence the choice of fittings
are as follows.
If dimensions are tight, then
depth of fitting may be important.
Some fittings are normally sus-
pended independently from the
parent-structure, which calls for very
accurate positioning if any work is to
be done before the ceiling is installed.
Others are supported on the saus
pended ceiling structure, but since a

3, GEC Modular fttings, left
with plastic diffuser support-
ed on Burgess res Clips,
right with open louvre -s,-
pendedfrom parent streure
in conjunction with Frenter
heated ceiling.

instead of sinking the lights witl
the surface of the ceiling you use t
trunking system which contains t
wiring to support the ceiling.
The SGB Flexible Grid is o
example which is used to support t
panel infilling in a complete modui
system, although it may be used
its own to carry individual lig
fittings. Perhaps the most adaptal
trunking is Inver-trunklng produce
by the AEI Group, 4, the'continuo
slot in the bottom being filled wi
a clip-in cover strip between fitting
By opening up the module of almc
any of the ceilings described in pare
of this article some 2) in., a strip
this trunking may be introduced
take the place of the standard st
pension and permit the flexit
arrangement of surface fittings alol
its length.
The transition between fitting at
trunking still manages to look rath
Improvised and could stand fourth
There are, of course, a host
flush tungsten fittings, mostly ci
cular, which may be incorporated
the ceilings already discussed, bt
they are far too numerous to examh
here. /

4, Inver-trunking system by ABI
Group. Left with Burgess ceiling,
right with Conduit Tee bolt. .

6 ft. 0 in. x 2 ft. 0 in. recessed fitting
and gear can weigh as much as 88 lb.
this arrangement might not always rull illuminated Ceili*gi
be possible. The veteran illuminated ceiling
As 2 ft. 0 in. fluorescent tubes in this country is the 'egg-cratA
with sockets will not fit into a louvre and it remains one of the mos
2 ft. 0 in. grid, some fittings are trouble-free in that it does not collect
designed so that the reflector box is dust and dead insects. Bearing ii
tailored to the module and the tubes mind the once popular ceiling pen
project through the sides to end dant bowls which still abound ii
plates which are not enclosed. This suburbia and so frequently are oves
may lead to the deposit of dirt from due for a scouring, it would seem tha
above and reduce the lighting to extend this principle to the entire
efficiency ceiling is not without its drawbacks.
Visible receded linking this problem with Modulume an
The visible recessed trunking sys- .claim that in a clean commercih
tem when used with a suspended interior, dry dusting should be carrie
ceiling represents the opposite ap- out at intervals of about two month
prach from that of recessed lighting: with complete washing or dam;

kS4liI L

cloth wiping every nine to twelve
months. No doubt this is quite
representative and assumes favour-
able conditions. Lumenated Ceilings
Ltd. offer special maintenance con-
tracts and cleaning facilities for
owners of large installations.
Modulunc pan diffusers are the
only ones available in strong colours,
which would, of course, be used
Corrugated plastic continuous strip
diffusers are usually fed into channel
support sections at one end, and
therefore present special difficulties
when the time comes for cleaning
the upper surface. There is quite a
wide variety of design amongst the
open louvre types and perhaps one
of the more interesting textures is
provided by Paragrid with 'bi-planar'
louvres which appear to be very
ingeniously designed for accurate
alignment and, like so many of the
more sophisticated suspended ceilings,
was not designed on this side of the
In most cases the void above an
illuminated ceiling should be de-
corated for maximum light reflection,
but the exception to this is the SGB
Flexible Grid which may be left
partly unfilled, in which ease the
parent structure and services would
be 'painted out' in a dark colour.
This is not strictly fully illuminated
and in any ease the lighting has
shallow integtal reflectors.
Whilst 'the louvre type ceilings
are, of course, acoustically neutral,
the void above may be lined with
sound-absorbent material. The modu-
lar illuminated ceilings (apart from
lonlite) depart from the 2 ft. and,
less commonly, 1 ft. modules which
are prevalent among the opaque and
sound-absorbent ceilings discussed
in the first article and adopt dimen-
sions which are appropriate to the
spanning capacity of the material
or may be conveniently integrated
with the available light iOttings.
Sylvalume and Lumcnator Module
ceilings both use a V profile for tlhe
visible portion of the grid so that
some light plays on the surfaces and
softens the joint. The Lumenated
ceiling, Sylvalumc and Modulume
can be fitted with perforated metal
sound-absorbent fins which are filled
with Fibreglass quilt and clip on to
the bottom of the supporting grids.
At present no figures are available
an their acoustic performance, but
they would appear to be more for
visual effect than for sound control.
The plastics which are incorporated
n these fittings consist of Acrylic
sheeting, Fibreglass, Polystyrene,
PVC and Vinyl.
Vinyl is non-inflammable and due
o Its low heat distortion temperature
will fall out of its supporting grid
mnd possibly help to smother the
lames, having the sprinklers free to
operate .
Acrylic plastic, however, has better
*olour and light stability, and
together with Polystyrene gives
betterr light transmission, but both
Translucent Fibreglass is only
tecepted by the LCC for rooflights
n comparatively thick sections as a
result of combustibility tests, whilst
'VC does not burn readily and in
ome forms may be self-extinguishing.
All these materials tend to produce
characteristic toxic gases when ex-
osed to flame and the prospect of
being trapped under a blanket of
aming plastic is not a pleasant one.
Finally it might be interesting to
ote that some architects have
fleeted a considerable saving by
counting a diffuser unit from a fully
laminated ceiling system in a

timber surround and casing made
by the contractor.

Atlas Lighting Ltd.
Infll: Aluminium 'cgg-crate' louvres.
Size: Standard panel 818 in. by 88 in.,
cell size 3 in. by 8 ill. by 8 in.
Joint: There is a double fin where
panels abut and the corners of panels
are chamfered to make way for the
suspension which terminates with a
visible circular clip stud.
Weight: Approximately 1 lb./sq. ft.
Light source: There is a 45 cut-off
and the depth of the void above the
louvres should be a maximum of
33 in. and a minimum of 18 in.
Finish: Normally white.
Approximate cost: Supply only,
including suspension, 20s./sq. ft.

Infill: Clear polystyrene interlocking
strips reeded on one side, which may
be assembled to form an 'egg-crate'
louvred panel.
Size: With practice a panel 821 in.
square may be assembled in 80
minutes. The cell size is 2 in. by 2 in.
by 9 in.
Joint: The panels are supported on
11 in. by 1I in. by in. aluminium
T sections (supplied by contractor)
or aluminium angles at the peri-
Weight: No information supplied.
Light source: There is a 45 cut-off
and the depth of the void above the
louvres can vary from 18 in. to
80 in.
Approximate cost: Supply only,
components and hangers (but not
including aluminium intermediate
supports where required) 13s. 6d./
sq. ft.

Infill: Opal plastic diamond pattern
'egg-crate' louvres.
Size: 10} in. by 0 in. panels with cells
I in. by 1 in. by I in. deep.
Joint: Panels are supported on trans-
lucent white polystyrene T sections
which may be cemented to one side
of panels at no extra cost.
1 in. by 1 in. T will span up 1 in.
to 4 ft. in. sag at
2 in. by 1 in. T will span up centre
to 7 ft. span
Weight: No information supplied.
Light source: No information sup-
Approximate cost: Supply only,
Louverex panels, 11s. 4d./sq. ft.
1 in. T bar 2s. 4d./ft. run.
2 in. T bar 3s. Od./ft. run.

Elco Plastics Ltd.
Elcoplas lighting louvre
Infill: Anti-static treated, light sta-
bilized plastic diamond or square
'egg-crate,' 5.
Size: Heavy pattern (1564) 51 in. by
5j in. by 1 in. (1i in. square cells).
Light pattern (1884) 10t in. by 9 in.
by 1 in. (It in. square cells). Also
in units 15 in. by 12 in. by If in.

r, Bkor igi u.
s, a A Ar ff &
0 a M Mr 9 aA

W 7a

6s, -i e igh0in- 0ors.

light pattern (2025) (2 in. square
cells). They are completely self-
supporting in panels up to 0 ft. by
8 ft.
Joint: Interlocking corners assure
alignment. Extruded plastic Ts are
available (0 ft. to 8 ft. long) to
support edges.
Weight: leather less than 12 oz./
sq. ft.
Light source: Angle of light cut-off
Finish: Opal colour.
Approximate cost: Heavy pattern,
2s. per unit 5) in. by 5) in. Light
pattern, 4s. 8d. per unit 101 in, by
0 in.
The panels may be out with a
hacksaw to fit any shape.

Harris & Sheldon (Elehsital) Ltd.
Paragrid tile (developed in Canada by
J. A. Wilson Lighting & Display Ltd.)
Infill: Anti-static treated, injection-
moulded polystyrene, 5.
Size: 1 ft. 4 in. by 1 ft. 4 in. with
'bi-planar' 'egg-crate' construction
forming I in. by j in. apertures.
Joint: The tiles span 1 ft. 4 in.
between 'U-trqx' suspended channels
and key together for perfect align-
ment. Tiles lift out for access to
Weight: 9 oz./sq. ft. complete with
Light source: 40 angle of light cut-
Finish: White pearl.
Approximate cost: 10s./sq. ft. includ-

panels are fixed to simple clips
suspended on the hanger rods, and
may be demounted for washing or
merely hinged down on either side
to give access to services and fittings.
Weight: 14 oz./sq. ft. complete with
Light source: Fluorescent tubes
should he mounted on the parent
structure at centres not less than
twice the distance between the
louvre tiles and the tubes. The
angle of light cut-off is 45.
Finish: Available in white, pale pink,
blue or green. The coloured louvres

8, Metal Sections' DifWte. Below, editions
through AA, left, and BB, right.

.... .. .-1 "

, Pararid b_ _Nw .k a -nd 7 H lit ue- -.
6, Pwagrid Vlnghta hi and 7, Hawaelift Lu-ri;l.

ing suspension (supply only). Light
fittings not included.

Handsale Luve-Tile (developed in
Canada by J. A. Wilson Lighting &
Display Ltd.)
Infill: Moulded styrene plastic, anti-
static treated, 7.
Size: 1 ft. by 1 ft. 'egg-crate' unit
St in. deep.
Joint: The basic units are clipped
together to form panels 2 ft. by 2 ft.,
2 ft. by 8 ft. or 8 ft. by 8 ft. The

Joint: The bottom flanges of the
galvanized pressed steel supporting
Ts are visible as a grid which may
also support some form of fibreboard
ceiling. The Ts are painted to the
customer's requirements and are
available in a very wide variety of
sizes to suit various hanger spacings-
Weight: Diffulite panels only, 4 oz./
sq. ft.
Light source: With fluorescent tubes
at 2 ft. 6 in. centres the distance
[continued on page 203

continued from page 202]
between the tubes and the Diffulite
should not be less than 1 ft. 0 in.
The angle of light cut-off is 45.
Finish: Standard off-white or any of
14 standard colours.
Approximate cost: Nett ex works for
quantities between 100 and 1,000
sq. ft. either off-white or one of
14 standard colours: Panels up to
4 ft. by 2 ft., 53s. Id./sq. yd. Larger
panels, 41s. 71d./sq. yd.
Above or below these quantities
there will be a reduction or increase
in cost respectively.
For special shapes there will be
an increase of 50 per cent on the
above prices.

Atlas Lighting Ltd.
Sylvalume (based on a system de-
veloped by Sylvania Electric Pro-

9, exampleo a Sylvalume ceiling.
ducts Inc. in the USA)
Material: Vinyl coloured diffusers or
acoustic baffles, 9.
Size: 8 ft. by 8 ft.
Joint: A 8 ft. by 8 ft. grid of alu-
minium extrusions supports the vinyl
pans, showing a projecting V cover
strip which catches the light and
reduces joint glare.
Weight: 1 lb./sq. ft. approx. (com-
Light source: This system consists
of an upper structure of primary and
secondary wiring and control gear
ducts with a flexible arrangement of
fluorescent tube sockets, from which
is suspended a secondary grid of
extruded aluminium ceiling supports.
Provided that the distance between
the tubes and diffuser is not less than
1 ft. 8 in. the rows if tubes may be
at 3 ft. centres.
For small areas or where the depth
it void is between 1 ft. 6 in. and 2 ft.,
standard batten holders may be
litted direct to the parent structure
and wiring ducts omitted).
Finish: Vinyl diffusers (see illustra-
tion)-white, pink or blue. Acoustic
baflles-white, black or red.
Approximate cost: Entire ceiling,
including framework, diffuser panels,
suspension and some baffles (ex-
!luding lighting system), is about
0Ls./sq. ft.

Coeatay, Pope (Electical) td.
lotlie 1
nfill: *Dogtooth' profile Fibreglass
______--- -- -t

0, Courtney, Popw'es Glos fit.inge. p and
weer left, detailed of Oeite 1. Boaom r'ioL, the
ims wiring dut supporting Godite 2 fill1
ize: 2 ft. 10 in. by 8 ft.
point: 5 in. by If in. by 16 gauge
averted m.s. wiring ducts, 10, at

2 ft. 11) in. centres suspended on
rod hangers and fitted with projecting
studs to support the infill panels.
The panels may be laid continuous
or broken by cross channels or solid
Weight: 2 lb./sq. ft.
Finish: White Fibreglass, and in
colours at extra cost.
Approximate cost: 117s./sq. yd.

Glolite 2
Infill: Corrugated PVC.
Size: 3 ft. wide by required length.
Joint: 5 in. by If in. by 16 gauge
inverted m.s. wiring ducts at
3 ft. 1f in. centre supported on rod
hangers and fitted with f in. by f in.
In.s. U channels each side to receive
infillpanels, 10. The panels may be laid
continuous or broken by cross
channels or solid panels.
Weight: 2 lb./sq. ft.
Finish: White PVC.
Approximate cost: 72s./sq. yd.
This firm also produce open
'egg-crate' louvres in metal with
2 in. by 2 in. by 1i in., 2 in. by 2 in.
by 2 in. and 3 in. by 3 in. by 8 in.
sizes, and moulded white opal plastic
louvres 12 in. by 12 in. with 1f in. by
1) in. cells 1 in. deep, all of which
may be made up into any required

Clompton Pukldnsea Ltd.
Modulume (based on a system
developed by the Wakefield Company,
Vermillion, Ohio, USA)
Material: PVC copolymer pans or
corrugated vinyl sheet.
Size: Pans 8 ft. by 8 ft. Sheet 8 ft. by
up to 30 ft. Expanded styrene panels
8 ft. square by I in. are also

12, Moduhum eating.
available for opaque sound-absorbent
nflling. For setting out 9 in. must
be added to the module dimension
in both directions. Where the room
size does not conform exactly, the
ceiling may float free of the walls, or
be furred out vertically to the ceiling
or horizontally to the wall, 11 and 19.
Joint: Fluted extruded aluminium
H sections normally visible, but may
he covered by a vertical clip-on
sound absorption baffle. Visible cross
Hs are used with pans only.

Weight: Pans and structure complete
-11 lb./sq. ft. Strip and structure
complete-1i lb./sq. ft.
Light source: Fluorescent tubes are
fixed in continuous rows 3 ft. apart to
wiring trunking, which in turn is
fixed to the parent structure at
approximately 15 ft. centres. The
distance between the diffusers and
tubes should not be less than I ft. 2 in.
Finish: Pans are available in trans-
lucent white or strong colours with a
non-reflective under surface and may
be fitted to project upwards (i.e.
coffered) or downwards. Corrugated

18, Jon W eeling.
vinyl strip is translucent white.
Aproximate cost: Coiling plus elec.
rel equipment 15s. to a2s./sq. ft.
(supply only and excluding wiring).
Framework and diffusers account for
50 per cent of this price.
Sound absorption: Perforated metal
fins in 8 ft. lengths and filled with
Fibreglass may be clipped on to
aluminium H sections in parallel
lines or a complete rectangular grid.
Ieantie Ltd.
Jonlife suspended ceiling
Infill: Perspex (plain, moulded or
with a regular design). PVC sheets
with a regular design. Hardboard
(plain or with perforations). Treetex
sound-absorbent panels of various
types, 18 and 14.
Size: 2 ft. by 2 ft. grid or 2 ft. by
any length. (Other grid dimensions
are possible.)
Joint: A pressed steel
channel stove enamel-
led in any required
colour can be sus-
pended either way up
to expose either pro-
jecting fins with dish-
ed buttons on every
intersection, a deeply
recessed joint with

ing intersection, or,
when this is fitted
with a slide-in cover
strip, a ceiling flush
with the supporting
grid. Cold cathode
tubes are recom-
Weight: No informa-
tion supplied.
Light source: No special require-
ments. This ceiling may be, but is not
necessarily, fully illuminated.
Finish: The variety of possible inill
panels is quite familiar and no
special properties are claimed.
Approximate cost: Os. Gd/sq. ft.
supply only, the suspension and
grid, ex works. 10s./sq. ft. supply
only, as above but with PVC diffusers.
Lumenated Cellings Limited
Lumenated ceiling
Infill: Corrugated vinyl diffuser.

Size: 8 ft. wide by a manageable
length. Re-lamping and cleaning
becomes difficult with, very lonj
Joint: Extruded aluminiuni H section
runners, showing a 1.80 in. cove
strip, or designed to take a clip-or
sound-absorbent fin. Hangers art
required at from 0 ft. to 8 ft. centres
Weight: No information supplied.
Light source: Not less than 8 in. front
the diffuser, 15.
Finish: No information supplied.
Approximate cost: 9s/sq. ft., supply

14, eonstramrdi of Jonlit ceiling showin
inverted wiring channel.

Lumenalor Module
Material: Vacuum-formed vinyl or
acrylic pans, Is.
Size: 2 ft. by 9 ft. trays or 8 ft. wide
Joint: Visible V-shaped extruded
aluminium track which is high-
lighted and therefore not obvious,
Hangers are at 6 ft. to 8 ft. by 2 ft.
Weight: 6 oz./sq. ft. complete with
Light source: Fluorescent tubes
should be more than 8 in. from the
trays, and in any case this distance
should be related to the distance
between tubes by the ratio 1 : 1I.
Finish: There are three standard
pans-plain or moulded in concentric
squares (see illustration). Specials to
Approximate cost: Os./sq. ft. (supply

15, e owtrudims f lmenated eiing.

41 0'
.. ,4 .
o o o o--t49,.a

lOVa Iow IO i 10/2',

Ilffoldina (Great Britain) Ltd.
--Metal Lathing Division, with
lighting by Courtney, Pope (Elec-
trical) Ltd.
SGB Flexible Grid ceiling
Infill: Solid panels with recessed
tungsten fittings or plastic or metal
louvred fluorescent fittings to ft the
grid, 17.
Size: Standard grid sizes are 2 ft. 8 in.
by 2 ft. 3 in., 4 ft. 8 in. by 4 ft. a in.
or 6 ft. by 8 ft.
Joint: A grid of 4 in. by 21 in. by
1I in. by 14 gauge galvanized pressed
mild steel conduit channel is sus-
pended from the parent structure,
showing a projecting fin.
Weight: Varies as the ceiling is often
arranged with only 50 per cent
nfillling (2 to 5 lb./sq. ft.).
Light source: The fittings are built
nto the panel infillings.
Finish: The grid is normally light in
.olour and since the light fittings do
sot rely on structural ceiling reflec-
.ion, both ceiling and hangers are
)bscured by dark decoration if some
anels are omitted.
approximate cost: Supply and fix
Sgrid ceiling based on a module
if 6 ft. by 8 ft.-66s. 6d./sq. yd.
supplyy and fix a grid ceiling based
in a module of 2 ft. by 2 ft.-102s.1
q. yd. Other grid sizes pro rata.
aube Lamination & Eagitneeari
'lasmalic diffuser panels
material: Anti-static treated poly-

styrene extrusion with small corru-
Size: 10t in. by up to 4 ft. (2 ft. and
4 ft. lengths standard), 10.
Joint: Deeply recessed V (lapped).
Weight: 10 oz./sq. ft.
Light source: Independent fluorescent
tubes 44 in. above joints (10) in.
Finish: Clear or translucent opal.
Approximate cost: 50s./sq. yd.
If the panels are over 4 ft. wide
then intermediate extruded poly-
styrene translucent supporting Ts
will be required, but they are
normally intended to span between
the extruded aluminium sections of
standard suspended ceilings. The
manufacturers claim that the
material has been tested to the
equivalent of 7,200 hours brilliant
sunshine without yellowing.

Electrically heated
Only two electrically heated
ceilings have come to hand at the
time when this article was compiled,
and both of these are adaptations of
non-heated ceilings. The first, the
Burgess system, consists of heating
cables laid over the firm's standard
metal tiles and backed with an
insulating quilt. The second, the
Heatacoust by Petradene Ltd., is a
prefabricated plaster ceiling, and
involves the bedding of the heated
element in the plaster tile which is


80 *virsng crOuit af Sreasi eeritcluy Aoeted
Wattage is 30 watts per sq. ft.
The surface temperature of the tiles
is 80' to 100" F.
The temperature of the cable is
1800 to 9000 F and that of the void
between tiles and blanket is 140 to
150 F. This gives a room temperature
of from 600 to 6 F.
Approximate cost: 73s. to l00s./sq.
yd. supplied and fixed.

Petwadne Ltd.
These tiles ae identical in ap
pearance to the Plater of Paris
'Supercoust' tiles described in the
previous article, but a eupro-sickel
wire wound around a silken core and
insulated with PVC is embedded in
the tiles between each row of per-
forations. This continuous heating
wire terminates at a plug in the
centre of the tile (with removable
brass prongs for packing) so that a
junction box (with socketed leads)
fitted to the structural slab above
can neatly serve groups of up to four
tiles without demanding any pre-
cision in initial electrical work, 21.
The system operates on an air
temperature of approximately 55 F
and the manufacturers recommend
one-third Heatacoust and two-thirds
Size of tiles: 2 ft. by 2 ft. or 1 ft. 8 in.
by I ft. 8 in. (specials to order).
'Watts: 60, 75 or 100 per tile.
Surface temperature: 1050 to 110 F.
Approximate cost: Based on an area
of 1,000 sq. yds. and assuming one-
third Heatacoust and two-thirds

1, aNlcamaut iw byia Prldet

identical in appearance (when seen
from below) to the same firm's
standard Supacoust tile. The latter is
one of the few heated ceilings which
have been designed in this country,
and has a logic and tidiness about it
which has great appeal.

Burgess Products Company Ltd.
Electrically Healed, Acoustic Tile
The metal pan tiles and spring steel
Ts are identical to those described
in the previous article, but mineral
insulated electric cables are fixed
to the general suspension and can
be connected to the normal power
circuit with a thermostatic control
which gives a quick response. The
usual sound absorbent blanket is
unrolled over chicken wire above the
electric cables to provide thermal
insulation, 20.

r 7W-'7j m J- '

22, as we-Sulr heated aeomttc Uiling.
must be in contact with the Burgess
spring steel T bars. A sound absor-
bent and heat insulating blanket
is laid over the heating -.coils, 22.
Three light fitting manufacturers
can supply module fittings specifi-
cally adapted for this ceiling. Hopes
Heating and Engineering Ltd. are
one firm of heating contractors
who will supply and fix this ceiling.
Approximate cost: 1l0s./sq. yd.
supplied and fixed.
Frengr Ceilings Ltd.
Frenger Suspended Heated and Acous
tic Ceiling
Although this ceiling may be
used without heating (i.e. the heating
coils left dry) it is essentially a heated
ceiling system.
I in. M.S. rod hangers (at approxi-
mately 4 ft. centres) hang from a
radial fixing box to take up
tolerances. On the hangers are
suspended 1 in. by 1) in. by 18
SWG channels which are weled
[continued on pae 206



Supacoust the cost for supplying
and fixing would be approximately:
63s./sq. yd.

Water-heated ceilings
By comparison with the electricE
heating systems these seem rather
clumsy, lit while the capital cost
arc evidently higher they are ni
doubt cheaper to run at present
even if there is the need for fue
storage and stoking. Looking ahead
however, one always hopes thai
electricity will get cheaper, anc
certainly one cannot foresee an3
similar hopes for solid fuel.
In all three systems it is important
to have a really good contact between
the tiles and the heating coils so that
the heat is conducted to the radiating
The Frenger ceiling would seem
to be the most straightforward, and
has certainly been widely used. More
light fittings manufacturers claim
to make modular fittings suitable
for this type of ceiling than any
Despite the co-operation of three
firms, the Stramax ceiling can wind
up with three separate suspension
systems, which surely seems rather
In the Burgess Sulaer ceiling, the
spring T bars which hold the tiles
are not connected to the heating
coils but must be held firmly against
them, and this would seem to call
for considerable precision.
The prices quoted do not include
electrical installation, light fittings
or connecting up to the heating
Burgess Produats Ltd.
Burgess-Sulzer Heated Acoustic
The Burgess metal pans and fixing
Ts are identical to those described
in the previous article, but the Ts
are supported by cleats to M.S.
angles which are suspended from the
parent structure. Hooked rod hangers
from the M.S. angles support sinuous
heating tubes at 0 in. centres which

r .. a 0ID

SZ ZZ Ls l continued from page 204]

23, Frenger suspended heated ceiling.
to the j in. O.D. sinuous heating
coils (at 2 ft. 0 A in. centres). 2 ft.
by 2 ft. nominal pressed aluminium
Pyluminized plain or perforated
pans are shaped on two parallel edges
to fit around the heating coil tubes
and held firmly in position by spring
steel clips, 28. These flanges being in
direct contact with the tubes act as
radiators. Bitumen bonded fibre-
glass 1f in. thick, faced with staple
tissue on the underside, is laid in
strips over the coils, and apart from
heat insulation this gives a rever-
beration absorption coefficient which
is highest in the middle range of
frequencies (i.e. 0.70 at 500 c/s.).
The panels are normally painted
with flat oil paint after erection, and
some eleven light fitting manu-
facturers produce module fittings
specially adapted for use with this
particular system.
Thermal capacity: Extremely low at
about 0.45 BTU's per sq. ft.
Approximate cost: 81s./sq. yd. sup-
plied and fixed would be a typical
price for a well insulated building in
the London area. (This is based on
a ceiling of 4,500 sq. ft.)
Stataax Cellings (GB) Ltd., Clark
and Fenn Ltd., and AEI Lamp
and Lighting Company, Ltd.
Stramax Heated Ceiling (developed

24, Stramax heated ceiling.
by Stra-Max International Research
and Development Centre, Zurich).
Stramax j in. I.D. pipe coils are
suspended by rustless hangers (which
need not be permanent) from the
parent structure, and a separate
system of secretly suspended steel
Ts support the 2 ft. by 2 ft. de-
mountable Clark and Fenn gypsum
plaster ceiling tiles (see previous
article) which for the heated part
of the ceiling are fitted with an
aluminium alloy cradle which must
touch the heating pipes and be
attached to them by a slotted saddle
clip, 24. A mineral wool blanket insula-
tion is placed over the heating coils
and separate sound absorbent pads
are fitted in perforated tiles. The
AEI Lamp and Lighting Company
can supply module fittings specially
adapted for this ceiling and inde-
pendently suspended.
Weight (without light fittings)
approx. 6 lb. per sq. ft,
With a mean water temperature
of 1500 F and a ceiling surface
temperature of 100t F the room
temperature will be 650 F.
Approximate cost: 00s. to 108s./sq.
yd. average (supplied and fixed).
Large well insulated areas 81s./sq. yd.
Small poorly insulated areas in a
remote district might run to 185s./sq.


path Production
Hilston Foundries Ltd., the makers
of the Allanta bath, have overflowing
order books. Seeing that present pro-
duction methods were unable to meet
demand, the company decided to
install completely new plant in new
premises. The most startling change
accomplished was that the number of
man-hours per bath dropped by as
much as 75 per cent. The fully
mechanized plant produces one bath
every working minute and so far as
is known it is the only one which has
been built from scratch for the sole
purpose of producing baths. The
intention is to increase production of
the Atlanta bath in all sizes, 54 in.,
60 in., 61 in. (available in two widths),
66 in. and 72 in. lengths. In the future
new designs will be produced in
response to demand.
Bilston Foundries Ltd., Highflelds,

Window Catalogue
James Gibbons Ltd. have issued a
new window catalogue which deserves
attention..It is divided into parts,
each of which has an ingenious
method cf referencing so that win-
dows incorporating various metal
sections may be appreciated without
constant page turning. One part is
devoted to double glazing units, and
there is also a section describing the
Windowall system of curtain walling.
The whole catalogue is bound so that
it lies flat on a desk or drawing board,
and generally should be found useful.
James Gibbons Ltd., 74 Southampton
Row, WI.C.I.

Guidance on Slates
Redland Stonewold Interlockil
slates have been available for son
time, and are becoming increasing
popular. Our attention has bec
drawn to a new brochure iliustratii
these slates. The point of interest
the low roof pitch. In the past thi
have been used successfully i
20 degrees, but the makers canni
undertake to guarantee them ;
waterproof at this pitch, though tht
are prepared to do so at 22j degree
provided that the supporting roi
structure conforms to their specific
tion. The cost of natural slate beir
so high relative to other material
Redland slates offer a very welcor
alternative. The brochure gives teel
nical information in a clear an
readable manner together with drav
ings of a complete suggested ro4
system. The interlocking slates al
available in three colourings, Liche
Green, Moorland Stone, and Slai
Grey, and the weight per Square
approximately 9 cwt. The size i
each slate is 17 in. by 15 in., minimum
headlap being 8 in. Another Redlan
product recently introduced to tl1
market is the Redland 52 Englis
Pantile, which, like all Redlan
products, is guaranteed for 30 year
A brochure illustrating this produce
has also recently been issued. Th
tiles are available in eight colours.
Redland Tiles Ltd., Castle Gatl
Reigate, Surrey.

School eight Fitting
A difficulty about choosing light
fittings for schools is that the mor
[continued on page 20
.. . .





... to benefit from their know-how and experience, simply write to:


Tynos Works, Scotswood, Newcastle-upon-Tyne, 5.

Telephone: Lemington 674658




continued from page 206]
pleasant ones tend to be too expen-
sive. A useful addition to the range
of choice is Siemens Edison Swan
Ltd.'s 'school fitting.' An opal glass
bowl is held by three knurled head

1, Siemens Edisn Swan opal glaus light bowl.
screws to an aluminium gallery,
which may be fixed to the ceiling or
suspended. The glass bowl has a
generous hand hole which makes
lamp replacement easier, and hence
increases the chance of actually
getting defective bulbs replaced by
caretakers-a practical point which
can save much annoyance. Prices
are not unreasonable and the fitting
is available in 200 watt and 150 watt
sizes. Clearly its use is not limited
to schools and it is to be hoped that,
though not spectacular, it may
sometimes be used to replace the
globe which hovers so ubiquitously
in offices and schools.
Siemens Edison Swan Ltd., 155 Char-
ing Cross Road, London, W.C.2.
Mere Sinall Pattensi tn Moela
Last month we welcomed a new

range of melamine sheet using very
small-scale patterns, as this seemed
to us the right way to use this smooth,
hard-and quite unprecedented-
material. Now another small-scale
pattern range has come in, 'chosen in
collaboration with' Ward and Austin

2, three examples of melains sheet* with small
(a firm of architects who have often
contributed articles to the AR), This
is the new Decorplast range, mar-
keted by Holoplast Ltd. It consists
of 47 new colours and patterns and
these are to be joined (and, by the
time you read this, will have been
joined) by seven photographic wood
veneers. Three of the patterns we
illustrate, to ful size, above. It will
readily be seen that patterns with

this degree of delicacy require that
the architect should show a corres-
ponding delicacy in his detailing.
e days of the clumsy cover-strip
ought to be over.
Holoplast Ltd., 116 Victoria Street,
Dohm Decor
A new and interesting material for
achieving brilliant colour externally
has just been marketed, known as
Dohm Decor. It is a finish which
can be sprayed on to, a prepared
surface of concrete, brickwork, ren-
der, wood, etc., and produce a
permanent decorative and water-
proof coating. It is inexpensive when
compared with natural facing ma-
terials (exclusive of labour, the cost
is between $s. and 4s. Gd, per square
yard) and it may also be glazed.
Basically it is conceived as a decora-
tive protective finish which may be
applied to most building materials.
The colour is good. The finished
surface is granular, and may be
cleaned down by normal methods.
It would appear to be a useful addi-
tion to the range of internal and
external colour finishes, and might be
employed very successfully on old
and new work alike. Time will expose
any weaknesses, but in the mean-
while it hakthe great advantage of
being easy to handle. Normal spray-
ing techniques are used and no
special equipment is required.
Dakm Ltd., 167 Victoria Street,
London, 8.W.I.
Coaeumers Control Unit fot Ua-
dolreor Heatiag
It is a sign of the times that under-
floor heating by electric off-peak load
is sufficient common for the manu-
facturers of equipment to produce

ancillary fittings specifically for it. We
illustrate below Midland Electric's
consumer control unit for' a heating
circuit only. The same firm also
produce a version which incorporates
both normal day load and night load





Our shAwreoom wilt a display of up-to-date schemes
are al your strvia and a eomapeent salts staf will
gladly rnder you and your clients i rrn assislanu

SNearest branch aewreoom address st:l on rtquest

L -
.. .
: o 4..

_~_ I_ __~~~~~~~~_ __ _1. 1.~_.~ ~___. ~~~_~__~~~_~. ~ _______ _~___ ~~_~~_~_.~__-I ~_I_ ---

~~~ ..
~ D

Continued from page 208]
off-peak switching. As you can see,
the unit is neat: it is also small, being
only 12 in. by 12 in. by 5 in. It is
cased in sheet steel and the cover is
Midland Electric Manufacturing Co.
Ltd., Reddings Lane, Tyseley, Bir-

Offices at Birmingham. Architect:
Erno Goldfinger. Assistant Archi-
sect: John Duncan. Quantity Sur-
veyor: Davis, Belfteld & Everest.
Engineer: Dr. K. Hajnal Konyi.
General Contractor: C. Bryant & Son.
Soil exploration: Ground Explora-
tions Ltd. Piling: Cementation Co.
Sltahion floors: Costain Concrete Co.
Precast concrete: Liverpool Artificial
Stone Co. Asphalt tanking and
roofing: Neuchatel Asphalte Co.
Thermoplastic floor: Neuchatel As-
phalte Co. Marble floors: Anselm
Odling & Sons. Suspended ceilings:
Clark & Fenn Ltd. Partitioning: The
Morris Singer Co. Thermal insulation
in ducts: Celcon Ltd. Metal windows:
Williams & Williams Ltd. Glazing:
Aygee Ltd. Arnourplate doors and
late glass: James Clark & Eaton
Ltd. Metahlork: Wessex Guild Ltd.
Ironmongery: J. D. Beardmore &
Co.. Paint: T. & W. Farmiloe Ltd.
Selvicesv: Heating and i ot water: Etna
Lighting & Heating Co. Radiators:
Copperad Ltd. Ventilation: Hopes
Heating & Engineering Ltd. Elec-
trical and electrical floor warming:
L. H. Banks. Sanitary fittings: Stit-
sons Sanitary Fittings Ltd. Lifts:
Bennie Lifts Ltd. Furniture: Hamp-
ton & Sons Ltd.
Nettingham University, Parlsad Build
lag. Contractors on the section

designed by John Wright, F.R.I.B.A.,
as follows: Main contractor: Trol-
lope & Sons (London) Ltd. Carpets:
I. and C. Steele Ltd. Wallpapers:
Cole & Sons Ltd. Chairs: L.M.
Furniture Ltd. Curtain fabrics:
Edinburgh Weavers Ltd. Fibrous
plaster: F. D)cjong & Co. Light
filings: General klcectric Co.
Nottingham University, Fine Art Wing.
Architect: H. T. Cadbury-Brown,
F.R.I.B.A. General contractor: John
Laing & Son. Acoustic ceiling tiles:
Tentest Fibre Board Co. Spot
light fittings and plastic egg-crate
ceiling: Harris & Sheldon Ltd.
Colour-matching fluorescent light
tubes: General Electric Co. Standard
light fittings: Merchant Adventurers
Ltd.; Geo. Forrest & Son. Metal
shelves and gallery: Sankey-Sheldon
Ltd. Gallery brackets and balustrade,
circular stairs, aluminium picture
rails: G. Johnson Bros. Ltd. Fabric
wall covering (Canoter): Arthur San-
derson & Sons. Carpets: Hampton &
Sons Ltd. Wallpaper: Primavera Ltd.
Tables, desks, cupboards, settees (de-
signed by the architect): Trevor,
Page & Co. Fibreglass chairs: Aidron
Duckworth. Upholstered chairs: Hille
of London Ltd. Door furniture: W. J.
Binas Ltd.
Offices at Davie Street, W.I. Archi-
tects: J. G. Austin-Smith & Partners.
Main contractor:. Holloway Bros. Ltd.
Sub-contracors: Venetian blinds:
Horsley Smith & Co. Electrical work:
Buchanan & Curwen Ltd. Suspended
ceiling: John Dale Ltd. Iron stair-
case: H. & C. Davis & Co. Iron-.
m~iogery: G. & S, Allgood. Fireproof
door: Dreadnought Fireproof Doors.
Flooring: Inlaid Rubolin. Door
handles: Comyn Ching & Co. Carpets
and curtain fabrics: Heal & Son.
Light fittings: Flurosel Ltd. Furni-
Sure: Libertys. Special typists' chairs:
Office Machinery Ltd.

Factory at Berkhassted. Proprietor:
Lake & Cruickshank Ltd. Archi-
tects: Architects' Co-Partnership.
General contractor: J. L. Constan-
tine & Co. Factory foundations and
reinforced concrete: London Ferro-
Concrete Co. Bricks: Pratt (Watford)
Ltd. Structural steel: A. A. Thorn-
ton (Teddington) Ltd. Special roof-
ings: W. H. Walker & Co.; IH. New-
sum & Co.loofing felt: William Briggs
& Sons. Patent glazing: Williams &
Williams. Patent and woodblock floor-
ing: Hollis Bros. Ltd. Central heating
systems: Weatherfoil Heating Sys-
tems Ltd. Electrical installations:
Rashleigh Phipps & Co. Sanitary
fittings: Adamsez Ltd. Door furniture:
A. G. Roberts Ltd. Fireproof doors:
Gliksten Doors Ltd.
Theological ColleI ei to Uan. Archi-
tects: Yorke, Rosenberg and Mardall.
General contractors: Bovis Ltd. Sub-
contractors: Ironmonger: H. & C.
Davis. Electrical work: B. French Ltd.
Tiling and tile mural: Carter (Lon-
don) Ltd. Terrazzo: Zanelli (London)
Ltd. Steel windows: Aygee Ltd.
Metal work: Wessex Guild Ltd.
Sanitary fittings: Stitson's Sanitary
Fittings Ltd. Block and strip flooring:
Hollis Bros. Ltd. Cork floors: Jos. F.
Ebner (1958) Ltd. Roofing: William
Briggs & Sons Ltd. Fire protection:
Associated Fire Alarms Ltd.; Read
& Campbell Ltd. Flush doors: Glik-
sten Doors Ltd. Roller shutters:
Haskins Ltd. Light steel trusses:
R. Smith (Horley) Ltd. Heating,
ventilation and plumbing: R. J.
Audrey Ltd. Duct covers: Broads
Manufacturing Co. Portland stone:
South Western Stone Co. Lift:
Keighly Lifts Ltd. Curtains: Heal's
Contracts Ltd. Furniture: Stafford
Furniture Ltd.; Russell Furniture
Ltd.i Hille of London Ltd. Purpose-
made furniture: Lord Roberts Work-
shops; H. Ventress. Light fittings:

Merchant Adventurers of
Ltd.; Fredk. Thomas & Co.
House at Coventry Architet
can Kay. General contract
Harris & Son. Sub-contractors.
roofing: Hugh Twaddle 4
Heating and hot water, a
heating with V. oil-fired unit:
tion Ltd. Sanitary fittings:
Fireplace & Sanitary Fittin
Wood blocks: Holis Bros
Lino floors: Limmer & 1
Lake Asphalte Co. Winda
ironmongery: James Gibbons
Flats at Lambeth. Architect
G. Creed. General contractors.
Ltd. Sub-contractors: Slate cil
Slate & Enamel Co. Refuse
Broads Manufacturing Co Re
TV installation: British Rela
less Ltd. Vermiculite screed:
Cheeseman & Sons. Heating
'Caledo.' Metalwork: Clark, I
Co. Glazing: Faulkner Green
Lightning conductor installat
W. Gray & Son. Insulation
Haine & Corry Ltd. Lift instk
Hammond & Champness Lti
cils and ventilators: Henry I
Sons Ltd. Storage tank: 1
Chambers & Co. Tiling: H. I
man Ltd. Partition slabs: Oake
Bricks:, R, Passmore & Co..
roofing dnd paving: Ragusa A
Co. Joinery: Rippers Ltd.;
Sadd & Sons. Flooring tiles: I
Ltd. Sanitary fittings: Stitson:
tary Fittings Ltd. Flue I
True-Flue Ltd. Electrical:
lWheeler Ltd. Ironmongery: Ya
& Co.


DUROMIT TILES--Decoratlve anI
trial. The only Tile with the dlama
aggregate. Agents wanted. Box lA

Plhltograpl take in I th
premises of Moons Motors,
Dutes Streel, Loandon.




SUNWAY SKYLIGHT BLINDS in this installation have been cleverly used by the
Architects for dummy decorative units and floating ceilings. The special
holding device fitted to all Sunway Skylight Blinds provides easy access to
the reverse side, the slats simply unclip and spring back into place.
MADE-TO-MEASURE in aluminium alloy and stove enamelled in 20 attractive
colours, Sunway Skylight Blinds are flexible, unbreakable, they do not
crack, chip or fade and will giSe a hlfetm: of trouble-free service with a
minimum of maintenance. They can be installed in a fixed or adjustable
position--alany angle-so if your problem is concerned with changing
heat and light conditions, ventilation, light reflection or artificial hghting
effects think of SUNWAY SKYLIGHT BLINDS and get in touch with


Sunday Industrial Dist r butors 2931



Plasterers' Tools, Appliances, and Plant-Labourers' Tools-Scaffolding-The Worshipful
Company of Plasterers-The Plasterers' Craft.

THERE is an old saying, that "a good workman is known by his tools "; and another,
that a bad workman always complains of his tools." Whichever may be the more
correct does not much matter. What does very much matter is that a good workman
should have a good kit '! and know how to take care of it. A thorough knowledge
of tools can be had only by long practice in the workshop and on the scaffolding.
A man may have hundreds of tools and be neither an artist nor a good mechanic.
On the other hand, he may have few tools and be both. The wisdom of the first saying
is revealed more in the way the tools are used and kept than in their number, whereas
a duffer can do little or nothing with the best and most ample kit in the world.
Among the plasterers' relics found by Dr Flinders Petrie at Kahun, in Egypt,
were two hand-floats, now at University College, London. One is 33 in. long and i' in.
wide, rounded at both ends, and slightly convex on the sole. The handle is the length
of the sole, as our modern panel-floats, and the whole float is cut in the solid. The
other is longer and has evidently been used for the rough coat. The sole projects
beyond the handle, more at one end than at the other, somewhat like our
modern skimming hand-floats. This is also cut out of a solid block. Both were
smeared with mud plaster as their owner had left them; they are the oldest known
plaster tools in the world, and were used for plastering B.c. 2500.
Fig. 33 illustrates plasterers' tools, plant, and appliances : A is the stand, B the
gauge board, and C the platform, nailed on the bottom rail of the stand; No. x;is
a laying trowel with a.double shank 2, laying trowel with a single," sharik ;' 3,
panel trowel; 4, margin trowel; 5, gauging trowel ; 6, smalgauging trowel; 7, largee
gauging trowel; ,8, a hawk; 9, ordinary hand-float; ro, cross-grained hand-float-: II,
skimming-float; 12, joint rule with stock; 13, small'joint rule with stock; 14, small
joipt rule without stock; 15, moulding knife; 16, plaster chisel; 17, level; 18, chalk-
line and reel; 19, fine drag; 20, coarse drag; 21, scratch drag; '22, bradawl ".',23,
tool brush; 24, large tool brush; 25, dister; 26, flat, wide stock brush; 27, four-tufted
stock brush; 28, hand-float for cement work; 29, panel-float; ,.30, fining-float with
round end; 31, fining-float with splayed end; 32, water pot'; 33, plaster plane ;:
34, lath hariuer;. 35; fine hand 'sieve; 36, gauge prt; 37, mitre, box; 38, squ re;
S39,:compass4s ; 40, plumb rule and bob ; 41 and 41a, scratches; 4, combined square,"
!-triangle, and level : 43, broom; 44, pail'; 45, tool bag; 4X, water measure; 47, tool
box; 48; darby; 49, plaster box stand ; 50, plaster box; 51; angle-float; 52, concrete
rule; .53, gauge rule; 54, niippers; 55,'traversing .rule; 56, feather-edge rule; 57,
saw; 58, splash brush.
Plate CII reproduces the phlotoftph of a set of plasterers' tools-of rather different


composition. It is interesting to compare the varying forms, which in the photograph
are of more recent make. Plate CIII, b, gives a series of American types from
a toolmaker's catalogue.

Banker.-A banker is used for gauging large quantities of material, the gauging
being done with shovels. They were in general use when hawk boys did all the
gauging for plasterers. Bankers are made about 5 ft. long and 4 ft. wide, with
boards 6 in. high on two sides and on end.


Brushes.-Good brushes are" formed with hog bristles nailed or bound on wood
handles with string, copper wire, or metal bands. Cheap brushes are formed with
grass fibre, etc. The principal brush is the stock brush, which varies slightly in size
and form. In some districts a brush having three or four tufts tied with string or
wire is used; in other districts a flat, wide brush bound with leather and nailed is
preferred. Tool or sash brushes are used for mitring, stopping, and general shopwork:
Fibrous brushes are generally home made. The hair is about 4 in. long, and tied on to
a handle about 6 in. long, i4 in. wide, and I in. thick. After the string is tied it is
saturated with hot glue. A hot iron is afterwards passed over the glue to bind the
hair together. Employers usually supply stock brushes (for whitewashing only) and
all shop brushes; the men find stock brushes and tool and water brushes for building
Brooms are made of split whalebone or metal wires, and are used for keying plaster-
work, sweeping scaffolds, paving works, etc. They are supplied by the employers.
Calipers are compasses with curved legs suitable for measuring the inside and
outside diameter of bodies. Hardwood calipers are made -with a movable centre,
so that proportions may be enlarged and reduced. Large calipers and compasses for
workshop use are usually supplied by employers.
Compass.-An instrument consisting of two movable legs for describing arcs or
circles, etc.
Chalk-line.-A long fine cord, on a reel, for setting out and striking long lines
on a flat surface.
Cradle.-A wood frame made to a desired concave curve and lathed and plastered.
It is used as a ground in forming, running, or moulding circular work. If the curve
is convex, the frame is called a saddle."
Drags are tools with toothed edges, usually made of thin steel plate of various
sizes and forms, for dragging surfaces straight or smooth, rough, and keyed for another
coat of material. A piece of an old tenon-saw blade, about 6 in. long, makes a handy
drag. A scratch drag is for keying the back of castwork before the material is set.
A useful size is 4 in. long and 2 in. wide. The teeth are made about in. wide, in.
deep, and I in. apart. A smaller set of teeth are made on the ends for scratching
narrow parts. The teeth should be undercut to give a good key.
Files and rasps of steel are used for finishing running mould plates and for
cleaning up plaster and carton-pierre. Coarse rasps are used for fining concrete work.
Employers usually supply files and rasps.
Floats and rules for spreading plaster on walls and ceilings vary in size and
form, and should be made of well-seasoned pine, free from knots.
Angle-float from 2 to 3 ft. long, 3 to 4 in. wide on each face, formerly used in
making internal angles true and square, but is now, unfortunately, obsolete.
Concrete floating rule, similar to a parallel rule, about i in. thick, 6 in. wide,
and of various lengths, with two hand holes to give power to the worker when floating
concrete, which is mostly done by beating with the edge of the floating rule.
Darby (48, Fig. 33).-A blade or sole, 3 ft. 6 in. to 4 ft. long, 4 to 5 in. wide, I to
Sin. thick, with two handles, each about 5 in. long and 2 in. in diameter, nailed or screwed
on the back of the blade at about one-fourth of the length from each end. The darby
is used for floating bays between screeds on walls and ceilings, and in some instances
for floating setting stuff to a fair surface, before hand-floating and trowelling. In
Scotland it is called a slack-float." Darbies are generally supplied by employers.
Feather-edge (56).-A wood rule, generally about 5 ft. long, 5 in. wide, and i in.
thick, with one end cut to an angle of 450, and one side splayed to an edge about 0 in.
thick, used for working and cleaning out angles, etc.


Floating Rules (55, Fig. 33).-For floating screeds and ruling off and forming fair
surfaces between screeds and flanking in bays ; vary from 8 to 20 ft. in length, 4 to 7 in.
in width, and i- to 21 in. in thickness. The back edge is tapered towards the ends, to
decrease the weight, give a counterpoise at the middle, and thus more power to the worker.
Gauge rules (53) are straight-edges with sinking at one or both ends. A
double gauge rule has a sinking at each end and is used for forming sunk surfaces.
A single gauge rule has a sinking at one end and is used for forming raised surfaces,
such as the plinth of a skirting.
Grooved Rule.-Considerable physical strength is required when working a long
floating rule. In some positions it is difficult to hold, and apt to slip out of the hands
or cramp the fingers. To prevent these evils, a rule made like a floating rule,
but having a groove on each side about 2 in. wide, k in. deep, and I in. from the
back edge is useful. To give grip, power, and freedom when working, and decrease
the weight of the rule, the size and position of the grooves vary according to the size
of the rule and the requirements of the worker. Two holes, each about i in. in diameter
in the sides, prevent warping, and are handy for hanging it up by. The plan and section
of a grooved rule is shown in illustration Fig. 58, p. 162.
Parallel rules of various sizes are used for levelling and for setting out parallel
lines. A useful size is 9 ft. long, 6 in. wide, and I in. thick.
Levelling Rule.-A long parallel rule with a wood fillet, on which a level is
placed for guidance when levelling ceilings, etc.
Plumb Rule.-A rule with parallel edges, a centre line and an opening at one
end to allow the lead-bob to work. It is used to try and adjust uprights.
Running rules (in Scotland rods ") are made in long lengths, about 21 in.
wide, I in. thick (planed on all sides and edges), as guides or bearings for running
moulds, for fences, and many purposes for scaffold and shopwork.
Straight-edge.-A long rule with a straight edge, used for testing the flatness
of surfaces.
Screed rules are generally 21 in. wide, i in. thick, and in long lengths as screeds
for laying concrete, or for giving a square edge or thickness to plasterwork.
Thickness rules are similar to screed rules, for a given thickness.
Traversing Rule.-A floating rule about 6 ft. long for forming screeds of gauged
putty or setting stuff, for running mouldings on, known as a justing rule in Scotland
and a sweeping rule in the North of England. Employers find all floats and rules.
Hand-floats are many and various. Panel and mastic floats are made of hard
wood. All other kinds are made of yellow pine. None are so suitable to the worker
as those made by himself. The float most generally used is a hand-float, about o10 in.
long, 4} in. wide, and a in. thick.
Cross-grained float is about ii in. long, 41 in. wide, and i in. thick. The
sole is cut with the grain crossways, that the sides may cut the work freely and last
longer. On the upper surface a dovetailed groove is cut, measuring I in. deep, 2 in.
wide at one end, and tapering to i[ in. wide at the other. A hardwood bar is made
to fit the groove, and on the bar the handle is fixed with screws. The bar strengthens
and prevents the sole from warping. Cross-grained floats are used for scouring the
setting coat of good three-coat work and for making angles square and clean. Float
soles soon wear thin, and it is desirable to keep a few in stock that they may get well
Skimming-float, from 12 to 14 in. long, 4k in. wide, and J in. thick, is used for
laying setting stuff and cements.
Panel-float, used for laying and smoothing gauged stuff in panels, also for
!mastic; is made of beech, pear tree, or other hard, light-coloured wood, which will


r cutting zinc. 7. Two-foot folding rule. Is. Chisel. 23. Gimlet.
r. 8. Spirit level. 16. Metal hand-float. 24. Steel dividers
9 I'arge wood pencil compaiscs. 17. Large gauging trowel 25. Bradawl.
above of small plaster to. Wood hand-float. 18. agingg trowel. 26-39. Set of small steel plasterer's tools.
r. Two metal set-.quarcs. 19. Margin trowel. 4. Plumb bob and line.
12 2a,. lath hammer. 41.1
sh. J3. Set of joint rules. 21. usingg brush. 42. Pincers.
14.) 22. Moulding knife. 43. Chisel
44. Trimming knife.

o. Scissors fo
i Screwdriver
2. Saw.
3. View from
4. Saw.
5. Splashbrus
6. Hawk.



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TOOLS. (The Goldblatt Tool Co., Kansas City.)



not stain the white plastic material. The soles are about 6 in. long, 3 in. wide, and
S in. thick; the top edges are splayed.
Fining-floats, varying from 3 to 6 in. long, from i to 3 in. wide, and from to
in. thick, are used for fining Portland cement mitres, cornices, panels, etc., and
where larger floats cannot be used. Workmen provide their own wood hand-floats.
Iron-floats (usually cast in one piece) are used for ramming and beating concrete.
Gauge.-A wood measure cut to a given length, for setting out equidistant
spaces and marks accurately and expeditiously.
Gauge boards and stances are grounds for gauging plastic materials on.
Composed of boards generally about 3 ft. 6 in. long, 3 ft. 3 in. wide, and 4 in. thick.
Two cleats are nailed across the back. A diagonal cleat fixed between them prevents
the board from warping. Stances, to support the boards, are made with four legs,
each about 2 ft. 6 in. high, a top rail fixed on all sides flush with the leg tops, and
another rail about 6 in. from the bottom. The lower rail should be boarded over as
a platform (as. shown at C on Fig. 33) for tools, etc., not in use.
Gauging boards for concrete (about 9 ft. square and i in. thick) are made in
two halves, to be easily moved; strong cross cleats project about 6 in. on one side of
each half, to fit together and keep the halves in position. The halves are sometimes
held together with hinges.
Gouges and chisels, similar to those of wood-carvers, are used for carving,
cutting, and cleaning up plaster, cement, and carton-pierre, etc., but their use should
be extremely limited and not allowed to infringe in any way upon the province of the
modeller. As explained elsewhere, plaster was intended by Nature to be modelled
or cast, and not to be carved.
Groovers (of various lengths), made of beech or other tough wood, are used for
forming grooves in concrete surfaces. A useful size is 2 ft. 6 in. long by 4 in. wide
by i in. thick; one edge is splayed on both sides into a flat V shape.
Rollers, for indenting concrete surfaces (for a good foothold), are made of brass,
with a series of projecting pins. The usual size is about 8 in. long and 4 in.
in diameter.
Jointers are small rollers, about 2 in. long, plain or corrugated, for indenting
the marginal edges of concrete slabs; one side of the roller has a rim about in.
projection for indenting a line.
The above three tools are employers' plant.
Hammers.-A plasterer's hammer (34) has a steel head, one end having a hatchet
blade (with a slot for extracting nails) and the other (the driving end) a hammer head
indented to prevent slipping. A wood handle is fixed into the shoulder of the head.
It is used for lathing and general scaffold work. A mounter's hammer, for driving
French nails and needle points when mounting composition, carton-pierre, etc., is
similar to an upholsterer's hammer. A hammer with aflat round head and a short
handle is used for piece moulding. Knapping hammers, as used for breaking stones,
are employed for breaking foundation materials for concrete. Knapping hammers
are supplied by employers ; lathing, mounting, and moulding hammers by the workmen.
Hawk (8. Fig. 33).-The board on which plaster is held, usually of pine, is about
I1 to 12 in. square, in. thick, splayed at the back about 4 in. wide, to leave the edges
about a in. thick. A dovetailed groove (about 3 in. deep by 31 in. wide, diminishing to
about in.) is made in the centre of the board, across the grain of the wood, and a bar
to fit the groove. Though usually made of pine, beech or other hard woods give greater
strength. The handle, of pine, about 5 in. long by 1 in. in diameter, is sometimes
turned, with a slight swell in the centre, and a knob at the end is fixed on the bar with
one thick screw, so that it may be taken off at pleasure. If fixed permanently with


three fine screws (the heads flush with the bar), the bar and handle can be withdrawn
in one piece and will serve for three or four boards. A clumsy way is to fix board, bar,
and handle in one piece, by two or three nails through the boards into the bar and
handle. There is a hinged hawk," grooved as first described, cut with a fine saw
down the centre of groove and hinged about I in. from the ends flush with the surface
of the groove, to keep the halves together. The bar and handle slide into the groove
and keep the hawk rigid. A leather or rubber collar on the bar will protect the
joints of the forefinger and thumb from damp and friction. American hawks are
from 12 to 14 in. square, sometimes of sheet iron with a wood handle. Hawks should
be light, strong, and damp-proof, for holding stuff and for gauging small portions of
stuff, provided by the workman.
Hod.-The hod varies in size and form, according to locality. The London hod
is the smallest, the American the largest, the Scotch the happy medium in size.
The London hod box is about 16 in. long, the sides 9 in. deep, and will hold about
two-thirds of a cubic foot of mortar, or about forty hods to the cubic yard. The
American hod box is about 2 ft. 4 in. long, the sides I ft. deep. The Scotch hod box
is about i ft. io in. long, the sides ii in. deep. The shank, 3 ft. 3 in. to 3 ft. 9 in. long,
is fixed a little in front of the centre of the box with a flat round block behind it and an
angle stay in front. A hod of this size will hold i cub. ft. of mortar weighing I0o lbs. ;
the weight of the hod (8 to 14 lbs.) added, the labourer carries over I cwt. in each load
of coarse stuff. One cubic foot of coarse stuff (allowed to this size of hod) equals
twenty-seven hods to the cubic yard. Hods are labourers' tools, sometimes provided
by employers.
Joint rules, made of hard wood such as pear tree and boxwood, were used for
mitring before steel plates were introduced. For long mitres, joint rules of pitch pine,
feathered on one side, one end cut to an angle of 75, and seasoned with linseed oil,
work clean and smooth. Joint rules are now made of sheet steel in various lengths,
3 to 4 in. wide and about i- in. thick; one end is cut to an angle of about 300; the
acute angle and one side is splayed about one-third of the width of the rule, leaving a
moderately sharp, straight edge. Scotch joint les have a thinner plate, let in (about
i in.) to a hard wood, mahogany or oak, stock," about 3 in. wide by in. thick, fixed
by two or more rivets. This wood backing or "stOck stiffens the plate, is more agree-
able to the touch, and less liable to cramp the fingers than a thin, cold, steel joint rule.
Knives.-Building knife blades are about 6 in. long; trimming knives from 4 to
7 in. long. A -small knife about 3 in. long, ground on both edges to a sharp point, is
useful for trimming the curves and eyelets of small perforated ornaments. A canvas
knife is thin and broad, with a square end, similar to a cobbler's knife. Moulding knives
are from 9 to 15 in. long. Composition knives are about 18 in. long, with a handle
at each end.
Larry (or Drag).-A three or four pronged rake, with a handle from 6 to 9 ft.
long, for mixing hair with coarse stuff and knocking it up for use. A rake, similar to
the larry, has a plain blade instead of the prongs, and is used for making setting stuff, etc.
Level.-A spirit level, the companion of the square and compass, is, as its
name implies, for laying levels and proving horizontals.
Mitring tools (Fig. 34A), or small tools of various sizes and shapes, of wrought
iron or steel, are used for mitring, moulding, cleaning out, stopping and modelling
ornaments. They vary in length from 7 to 1i in. The principal one has a leaf or
spoon-shaped blade at one end and an oblong rectangular blade at the other. The barrels
should be octagonal in section and thick at the centre. A round barrel is apt to turn or
slip; a small one to cramp the fingers. I, a small tool with a square end and a leaf
end, is used for mitring and stopping; 2, a small spade tool with one end square and


the other a trowel or spade-shaped, is useful for laying and pressing gauged stuff on the
back of the cast and for many purposes; 3 is a large mitring tool with a leaf end and
a square end; 4, another mitring tool with a pointed leaf end and a round leaf end,
for mitring, bedding, and cleaning out; 5, a double square-ended small tool with
one blade i in. wide, 2 in. long, and the other in. wide by i- in. long, is useful for
laying and finishing narrow spaces, cleaning out when fixing blocks, and for work
where the margin trowel is too large. Bone tools, hollowed to fit different sized beads,
were once used for beads when mitring. A few tools with the blade end straight and
the other curved, having the edges serrated, are useful for working circular work, or
where the plaster is full. They are commonly called scratch tools."
Scratch Tools.-Fig. 34B shows various scratch tools: i is one of many gouge
tools, for carving mitres and cleaning up; 2 is a double-ended scratch tool, curved for
working down mitres and circular work; useful for cleaning up and for modelling
cement or plaster in situ; 3, 4, and 5 are scratch tools useful for circular mitres and
other work; 6 is a stopping tool with a leaf end and a spear end, one edge of which
is serrated and the other plain; useful for many purposes.
Pails, of galvanised sheet iron, to hold about 4 gals., are usual. Wood pails, to
hold 3 gals., are used in some districts. Putty pails have an extra handle on the sides.
Employers provide pails.
Pinchers or nippers of steel for extracting nails, twisting wire, etc., are provided
by workmen.
Radius Rod.-A wood or metal rod for running circular mouldings. A running
mould is fixed at one end of the rod and a hole made in, or a metal plate fixed on, the
other end to fit a centre pivot. In Scotland it is known as -a gig-stick and in some
districts as a trainer.
Planes, for levelling down and smoothing plaster surfaces, should have toothed
Saws, about 18 in. long, are used for cutting running rules, mouldings, etc. A
fine-toothed saw is best for fibrous plaster. Employers provide saws for shop work only.
Scaffolds are temporary erections of timber and boards to work from and place
materials and tools on. In Scotland, plasterers erect their own scaffolds. For ordinary
sized rooms the uprights, called sipheads," have a slot at the top to receive the
needle or transom. The scaffold has battens 7 in. wide by 21 in. thick, placed about
7 in. apart. In England, regular scaffolders are employed. The transoms are tied
on poles with cords; the scaffold is clad with boards 9 in. wide by il in. thick, laid
close together.
Scratch.-An implement generally of pine, about 14 in. long, 7 in. wide, and
in. thick, with teeth about 3 in. long, the points about i- in. apart. A simple and
effective scratch may be made by fixing four laths together and tapering the points.
Good and durable scratches may be made of thin metal plates, or strong wires inserted
into a wood handle. Employers supply scratches.
Screen.-An upright sieve about 6 ft. long by 3 ft. wide, with sides 6 in. deep.
It is fixed at an angle of about 450 for screening lime and sand which are dashed against
the wires ; the finer parts pass through, leaving the coarser parts on the inside. Screens
being "plant," are supplied by employers.
Plaster small tools, similar to mitring tools, are useful for shop work. A few
extra shapes are required for cleaning up originals. Brass small tools are useful for
cleaning up plaster, and are generally made by the user out of brass rod about I in.
thick, cut a little longer than the length of tool, to allow for cutting off ends, which
generally split while being beaten out flat. File the ends to the desired shape. The
barrel is filed to octagonal form to prevent them from turning in the fingers. Waxed


string wrapped round the barrel will give a soft, easy hold. Fig. 34c shows a set of small
tools for working plaster. They are made largely in Paris, and extensively used for
general shop work.
Sieves or riddles of varying size and fineness are used for running and riddling
lime and washing sand. A riddle rest is used in some districts to carry the weight of
the riddle and lime. It is rapidly moved backwards and forwards by one man, while
another fills it. As the lime forms into heaps, they move back a little, until finished.
Putty sieves have a fine wire or hair mesh on a wooden frame with two handles.
Punching sieves (used in some districts for making setting stuff) have a wooden frame
about 2 ft. square by 7 in. deep, on which a strong, fine steel wire mesh is fixed. A
wooden punch (like a large hand-float for both hands) is used to punch the putty and
sand through the mesh into a tub, on which the sieve is placed.
Squares (set squares), of wood or iron, of various size, are useful, particularly one
about I ft. each way. Being triangular in form, the 450 angle is useful for mitre
joints. They are sometimes made with a level or small plumb-bob attachment, or
with both, and are useful in forming small works plumb and level. One about 6 in. is
useful for return mitres, etc. Wood squares, about 3 ft., are required for large work on
ceilings, bench, and other work. Employers provide large squares; plasterers provide
their own small ones.
Templates (circular running rules and screeds) are cut out of pine boards
to the desired curve. Plaster templates are used for running clay profiles, etc.
Tool Box.-Usually about 18 in. long, 14 in. wide, and 12 in. deep (inside
measurements). A movable tray 5 in. wide by 21 in. deep, placed on runners inside the
box, is useful for holding small tools. The box is usually carried by a strap fixed to
the handles. "American cloth" bags are useful for keeping tools. In some districts
tools are simply tied up in an apron.
Trowels, of various shapes and sizes, have each their own particular use.
Tyzack, of London, is a noted maker of plasterers' tools, his trowels being in general
use throughout the United Kingdom.
Laying Trowel.-The most important of its kind. A constantly used tool for the
plasterer, about io in. long and 5 in. wide. The plate is made of the best steel, light
and flexible. The shank is riveted on to the plate with three (sometimes four)
rivets. Some trowels have two shanks (without tangs), one at each end, made with a
flat round head with a countersunk hole, to receive screws or a long rivet.
Polishing Trowel.-A half-worn laying trowel. The edges should always be
straight and parallel, or nearly so. Parallel edges work truer than tapered edges.
Margin Trowel.-Is used for laying and polishing margins, styles, or spaces
where a larger implement could not be employed, similar to a gauging trowel, but the
edges of the blade are parallel and the end cut square. The blade is about 31 in. long
by 2- in. wide. The handle is shorter than that of a gauging trowel.
Angle Trowel.-A novel tool for finishing internal angles; is similar to a margin
trowel, but has the two side edges of the blade I in. deep, turned up at right angles to the
blade, perfectly square, and the points of the turned up sides cut back at an angle of 450.
Panel Trowel.-Used for setting small panels; is similar to a laying trowel, but
the blade is thin and springy, and is about 5 in. long, 3 in. broad. The handle is slightly
shorter than that of a laying trowel, for easy working in small and deep panels. A good
panel trowel can be made out of an old laying trowel.
Gauging Trowel.-For gauging small portions of stuff on a gauge board or
hawk, and for laying stuff on mouldings, mitres, etc. The most useful blade is about
6 in. long by 3 in. wide at the heel or handle end, tapering to a narrow point at the
other end. The shank and blade are sometimes made separately and riveted together;









more often than not they are forged in one piece. The wooden handle is bored to
receive the tang of the shank, and partly filled with powdered resin and plaster. The
tang is made hot and pushed in; the heat, melting the resin, forms with the plaster a
strong cement, securing the tang and handle.
Laying Gauging Trowel.-Similar to, but much larger than, the ordinary gaug-
ing trowel; is used for laying gauged stuff on large mouldings and for bedding large
plantings. The blade is from 7 to 9 in. long by from 3 to 31 in. wide at the heel end,
tapering from i1 to 2 in. wide at the point. The small gauging trowel, generally an
old one which has been worn small, and ground to a sharp point, is used for stopping
small holes, scraping and cleaning rules, etc. The handles of gauging trowels, now
generally made of ash, with deep brass ferrules, were formerlymade of mahogany or ebony.
Tubs.-Vary in size (according to requirements). For holding water, washing
sand, slaking lime, etc. An old spirit cask cut in half makes two good tubs.
Plate CIII illustrates a set of- wire and boxwood modelling tools, caliper com-
passes, syringe, and sponge.
Plasterers' Plant, Labourers' Tools, and Scaffolding.-The annexed
illustration (Fig. 34) shows plasterers' plant and labourers' tools: i. Scaffold trestle,
also used as a hod-stand, as shown. 2. The hod. 3. Putty pail. 4. Shovel. 5. Larry
for coarse stuff. 6. Water tub. 7. Riddle rest. 8. Putty sieve. 9. Sand screen.
io. Sliphead. xi. Putty slack box. 12. Banker. 13. Putty rake. 14. Hawk boy's
server. This latter tool is now obsolete, and is only given as a relic of the past. (See
description in Chapter XIX, p. 321.)
Cleaning Plasterers' Small Tools.-Plasterers usually clean their small tools
with a piece of wood dipped into setting stuff or brick dust. This brightens but wears
them more than working with them, scratches the surface and spoils the edges. They
should be cleaned daily when in use by wiping them thoroughly dry. Rust destroys
them. If dried when done with, they will keep clean and smooth. Some plasterers
make their own small tools out of old files or fencing foils. A deep black polish can
be given to all small tools as follows : Boil i part of sulphur in io parts of oil
of turpentine;- this produces a brown sulphurous oil. Warm the tools, brush the hot
solution slightly over them, and heat over a spirit lamp or slow fire until black polished.
Tools thus polished should not be scrubbed, but wiped clean and dry after use.

FIG. 34A.-Mitring Tools. FIG. 34B.-Scratch Tools. FIG. 34c.-Small Working


coats only are needed, the second following the first in twenty-four hours. Sawn or
cleft laths may be used. The former give a more uniform surface and require less
material. Sirapite is gauged in a "banker" as for ordinary cement. On brickwork,
gauge with 3 parts clean sand and a small proportion of lime putty to I part sirapite.
On lathwork, a gauging of 2 parts of sirapite to i of sand, with a little lime putty, is best.
The laths should be nailed 'a- in. apart. The finish is usually gauged in a pail of water,
allowed to settle, and the surplus water poured off. It is laid and trowelled off as for
gauged putty and plaster. Excessive gauging or prolonged trowelling should be
avoided. For metal lathing mix sirapite and common hair plaster half and half for a
first coat.
For uneven walls and other reasons sirapite is often used half and half with
common lime plaster, or on lathwork with common hair plaster. The work is kept
thin and is done in two coats. It is finished quickly and makes excellent work.
Sirapite plaster can be safely used on Fletton bricks. With the special precautions
given by the makers there is no discoloration of the plaster which often occurs with
these bricks.
Sirapite is largely used on metal lathing and steel sheeting. Dr Gerald Moody,
F.I.C., F.C.S., of the Central Technical College, South Kensington, conducted some
experiments in March 1905 as to the action of sirapite on such lathing, and his report
concludes as follows: My analyses show that neat sirapite is entirely free from any
acid constituent. From a chemical point of view, a material having such a
composition as sirapite, and used, either neat or mixed with lime putty, would be
expected not only to be non-corrosive of metal, but to actually protect bright sheets of
iron and steel from rusting. In order to investigate this question, a number of perfectly
bright sheets of iron and steel and of expanded iron' were partly covered with sirapite
plaster and then exposed to an atmosphere charged with much moisture and acid
vapours. After seven days' exposure the uncovered parts of the metal were thickly
corroded and pitted with rust; whereas on removing the plaster from the covered
portions of the sheets the metal thus laid bare was found in every case to be bright.
Direct observation therefore confirms the conclusion, deduced from a consideration of
the chemical composition of sirapite, that sirapite has no corrosive action on metal;
but that, on the contrary, its effect is to prevent the rusting of iron and steel."
Sirapite is most convenient and economical for all kinds of plastering repairs.
Like all gypsum plasters it should not be used in permanently damp places such as
basements where no proper damp course is present. The walls should be dry before
being coated. Applied to Portland cement concrete; the work should be dry before the
sirapite is put on.
Wood Lathing.-Wood lathing is used on wood joists, studding, etc., for
plasterwork on ceilings and partitions. Plastered partitions were introduced about
the end of the sixteenth century. Lath wood is straight-grained wood; the outsides of
fir trees are split into laths. Red Baltic timber makes the best laths. Lath rendering
or splitting was formerly done entirely by plasterers, and was a profitable source of
employment during winter months. Lath driving or nailing was also allotted to
them, but owing to the subdivision of labour, lath-splitting and nailing in most large
towns has become a branch trade, although it is in some places still done by plasterers.
Laths were formerly all made by hand. A large quantity, however, are now made
by machinery. The latter are known in the trade as sawn laths." An old method
of lathing was done by sawing broad timber into thin boards about in. thick, and in
width from 3 in. upwards. The boards were split in position to give a key. Samples
of this class of work are still to be found when repairing old plasterwork. Laths are
now made chiefly from Baltic or American timber. This should be specially selected,


cut into lengths, and split by wedges into bolts," with a dowel axe into fittings," and
with a chit split into laths."
Laths are usually purchased by the load, bunch, or bundle. A bundle of ceiling
laths is computed to contain 500 lineal ft., but in many parts of the country they are
still reckoned by the long thousand or 1,200 ft.; hence a bunch will contain 100
4-ft. laths and a bundle will contain two bunches, and will cover 7 yards superficial.
A standard bundle should contain seven score 3-ft., six score 4-ft., and five score 5-ft.
laths. These terms and quantities vary according to locality. Machine or sawn laths
are superseding hand-made laths. Those split by hand give the best work. They

FIG. 35A.

split with the grain of the wood, are therefore stronger, and less liable to twist than
machine-made laths. Cast-iron nails are used for common work; wrought nails in
high-class work. Galvanised wrought-iron nails prevent rusting. Laths should be
selected in lengths best suited to the spacing of the joists from centre to centre, and
should be fixed about 3 in. apart. In common work the ends overlap. In good work
they should butt against each other. This is termed butt work." They should
also break joint in bays every 3 or 4 ft. in width, to give a better key and prevent any
cracking of the ceiling or wall along the line of joists, as shown in Fig 35A. When
ordinary laths are used, the studding and joists should never exceed 14 in. from centre
to centre. The thickest laths are used for ceilings, lath and a half for partitions, and
battened or studded walls for good work. Single laths are used for ordinary work,
stoothed walls, or partitions. All timbers over 3 in. wide should have fillets or double
laths nailed along the centre and the laths nailed to them. This is done to give a better

Zakhn7 y/or Ceitlys, Parlirrons c.

Floor Joists or Partition Studs


S' -" -Laths (_Lath-and-/Hal) 3/8"a apart-.



SBreak point everti 5 or6 la/ks. c.. .2s
-- .----- I---- 0,,-


key to the plaster, and is known as counter-lathing." Reeds, wickerwork, slates, and
wire have been used as substitutes for wood lathing. Wire and metal sheet lathing are
now preferred for fire resisting and material saving. The by-laws of the London
County Council require all laths used for plastering to be sound laths free from sap,
but iron or other incombustible laths, wire netting, or other suitable materials to
the satisfaction of the district surveyor, may be used."
Expanded metal lathing plays a very important part in the plastering of modern
buildings, and is a paramount necessity in all large buildings.
The expanded metal lathings as made by The Expanded Metal Company Limited
(London and West Hartlepool), are made from mild steel sheets. They give an ideal
key for plaster ceilings, steelwork encasing, solid and hollow partitions, exterior walls,
and other work. Two types are manufactured and known to the trade as-
B B Expanded Metal Lathing.
Expamet Expanded Metal Lathing.
SBB expanded metal lathing (Fig. 36A) is made in sheets 9 ft. by 2 ft., from
26, 24, and 22 gauge mild steel, in weights varying
from 21 lbs. to 3- lbs. per yard super.
"Expamet expanded metal lathing (Fig. 36B)
is made in sheets 6 ft. by 2 ft., 7 ft. by 2 ft., and
8 ft. by 2 ft. 3 in., from 24,
22, and 20 gauge mild steel,
in weights varying from 3A
lbs. to 5 lbs. per yard super.
Expamet" lathing,
the older type, is made on
a vertical cutting machine.
The "B B" lathing is a
new invention made on
rotary machines, which run
FIG. 36A.-" B B at a much higher speed and FIG. 36B.-" Expamet"
Lathing. produce more cheaply than Lathing.
the vertical machines.
"BB expanded metal lathing is recommended most. It was designed to
combine all the best properties. The meshes are a small diamond shape. From their
shape and size a minimum quantity of plaster is required, and very little material
is wasted.
Both lathings are coated with a mineral oil during manufacture and dipped in
asphaltum paint.
Unpainted lathing is unsuitable for plasterwork; lathing required for other
purposes may be uncoated.
Metal lathing can be galvanised, but is more costly.
BB expanded metal lathing can be made from galvanised blank sheets; but
the edges of the strands are uncoated.
It can be obtained also in the form of corrugated lath; the standard corrugations
are I in. wide by in. deep overall, are contiguous and run the long way of the mesh,
viz., the long way of the sheet.
Generally both kinds are suitable for all purposes to which metal lathing can
be applied. All of the meshes are suitable for hair plaster. The "B B and in.
meshes are best for hairless plaster.
The 26 g. weight is for solid partitions, steelwork casing, and similar work.


Nothing lighter than 24 g. lathing is advisable for ceilings and similar work; 26 g. B "
is good for small plain ceilings.
For heavily ornamented plaster ceilings and other work, tiling, mosaic, and exterior
work, the heavier lathings are more suitable.
Painting, etc.-All metal accessories, clips, hangers, ceiling bars, tension rods,
and lathings used with plasterwork must be painted. Where excessive moisture is
apprehended, galvanised lathing, if not back-plastered, is best.
Spacings.-For ordinary plain, horizontal, and sloping work-
No. 250 may be used at spacings up to 12 in.
Nos. 252, 1, and 26 for spacings up to 14 in.
Nos. 254, 91, and 93 for spacings up to 16 in.
Nos. 92 and 94 for spacings up to 18 in.
Fixing.-Metal lathings should be fixed securely, long way of the sheet across

the bearers, to ensure a level and rigid ground
for plaster. The strands of the' sheets should
slope in one direction; for vertical work they
should slope inwards and downwards.
The lathings should be fixed at intervals-
not more than 4 in. for the lighter, or 3 in. for
the heavier-by staples or nails to woodwork, or
wire clips to steelwork (Fig. 37), and wired
together at similar intervals between supports.
The sheets must overlap not less than one mesh
where they join. Sheets should be bent to give
a proper key for the plaster. Overlaps must
not be made at angles or curves, but about 2 ft.
Galvanised slice-cut staples i iil. or il in.
long are intended for woodwork. No less than
18 g. galvanised soft iron wire is required for
tying. Special lathing clips are made for clipping
the lathings to flat ceiling bars, cradles, etc.
To clear the lathing from the face of joists.
studs, etc., for a good plaster key," a small
round rod or a strip of hard wood should be
clipped or stapled on to the face of the
structural member.



FIG. 3

1sT -



Plasters for Expanded Metal Lathings.-Ordinary lime and hair mortar,
plasters with a natural basis (such as suitable quarry or river sand), or those gauged
with Portland cement, which tend to preserve metal, are recommended for use with
expanded metal lathings.
Plasters and mortars containing ground ashes are unsuitable. Boiler ashes,
cinders, or other materials containing corrosive chemicals must be avoided; in fact,
plasters and mortars containing sulphates, chlorides, or other corrosive ingredients
should not be used on metal lathings.
Lime and hair mortar is cheap, efficient, and fire-resisting.
Plaster should be mixed stiff and applied without excessive pressure. If too
much pressure is used, the lathing in a bay newly plastered will spring or give to the trowel
and the newly finished plaster fall off. Pockets or holes must not be left in the body
of finished work. The moist air returned by them is liable to set up corrosion of
the metal.


Suspend de d
fxpan dad Melal
JPeel Joist or
Roo/ Princzpal

Distance of Ceiltnq from
bottom flan oe of joit- /s
varied by length of/any

/"' '4 Ba.r

Ceil/nRys n Dealad
A and rK P/aster.

3/4 x 1Z te S teel _
i _. ."nanfsr C.j I pert j "
P se.: e. .,...
Expanded Me-tal h/ad to Ceilin Bars wilh 18i C.l. Wire at 53 o intruvals

i/ I 2 4 .5 7 e. a9. 1/0. Inches
I I------ -- -\ coele ,/^

FIG. 38.


Ceiling line.,

floor line i

)- N!2TE' Thir mal-
ib Timber Jtuds. erzal Is mrnde
.- --- --- up into sheets
Fac of PLAN \t M lathin 9'-O'long by 2-0
V %x %' /1erP Expanded AMe/al[-
/ For Partitions \ ire For Ceilnys etc
[<-----J--3-----+1 1------- 5' -----------^
4 Reinforcing rod in Concrete flooring rib.
"' 31/'dia wire at /2" intervals along '4 to suspend 'C
'"' %" dia. rod suspended from 'Y'wirej.

bI:.. Concrete I-/- flroo-r .

'Ribmet tied at each rib to 'Crods
with 16 gau9e G.I wire

FIG. 45.

G.f.B. Of






.... .- '.
I'x '/4 '.

I x /4 0


FIG. 99.





BENCH r ti J O -4- LINE.






~~ "'"




ceilingIN G


t-- -- O




FIc. 101.






FIG. 7.





FiG. 102.











FIG. 103.

Fig.. K

L Fi.6.






FIG. Iog.-Casting Fibrous Plaster Enriched Cornices by the Bedded Enrichment System. Reverse
and Framed Wax Moulds for Enrichment.

:' B

: ::.TI$ a?
:::::i~::-.( :: ::





1111121 (1






3"x 4 cROUDS. .

I" x '. NAILS THUS I--

FIG. 112.-Fibrous Plaster Panelling, Ceiling Beam, Beam Casing
Entablature, and Coffered Dome.

I _

S1I'- I .


sawdust, fibre, wood wool, or ashes are occasionally used as aggregates. They are
made in various forms and sizes, according to purpose. For partitions they are generally


Oalod 0o0ijvs
&7'a&. -Z -?---"



*'^Od / alO V)S

o >

^ "a x -4
an 0
.. L -E

3 ft. long, i ft. wide, and 21 in. thick. Every three blocks of this size measure 2 yards
superficial, counting both sides, and each block weighs from 15 lbs. to 25 lbs., according
to the size of the perforation, the amount and class of aggregate. They are made with
round perforations extending longitudinally from end to end. This is done with rods

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