Good wood houses are built of dry lumber

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Title:
Good wood houses are built of dry lumber
Physical Description:
Unknown
Creator:
Teesdale, L. V
Forest Products Laboratory (U.S.)
University of Wisconsin
Publisher:
U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory ( Madison, Wis )
Publication Date:

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Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 29221241
oclc - 236971672
System ID:
AA00020507:00001

Full Text

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GOOVD WOO(D tIIUSES AIPIE BUILT

01r DRIY LUMBIErI


May 1946


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No. R1613 i









UNITED STATES DEPARTMENT OF AGRICULTURE
FOREST SERVICE
FOREST PRODUCTS LABORATORY
Madison, Wisconsin
In Cooperation with the University of Wisconsin


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GOOD WOOD HOUSES ARE BUILT OF DRY LU!EER


By L. V. :ELLESDALL, Engineer
Forest Products Laboratory,- Forest Service
U. S. Department of Agriculture





Wo need homes in this country, millions of them, nob only for our

GI's, but for untold numbers of families whose present housing accommoda-

tions are inadequate. The buyers of these houses expect them to be permanent

homes, well constructed and comparable to the type built in nre.':.Ar day .3.

They will not be eual, however, unless the manterials used are equal to those

used in the past. One inrortant difference is the lack of stocks of seasoned

lumber and the fact that green or unseasoned material may be used.

The tremendous de.-and for housing will require an enormous amount of

lumber. Because preser-t lunb-r stocks are practically exhausted the lumber

required must be produced from trees now standing in the forests. Freshly

cut lumber is green, that is, it contains a lot of moisture or sap. This

moisture should be removed before the material is suitable for use. The

sawmill ca-.acity of this country for ordinary peacetime needs in the past

has been somewhat greater than is req-ired to fill orders for lumber so that

stocks have accumulated at the sw.'nnmill and in wholesale and retail yards.

Time wvas thus allavied for stock to be adeq otely dried or seasoned before it

was finally sold to the consumer. During periods when the demand for stock

exceeds the capacity of the mills, however, the stock on hand becomes smaller

and smaller, the time allowed for seasoning decreases, and if the demand


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Maintained at lMadison 5, 7Nis., in cooperation with the University of
Wisconsin.
Report No. R1613 -1-






becomes Creat enough the lumber may be sold as fast as it can be cut and

without time for seasoning. Such a condition of demand exceeding the pro-

duction began to develop before Pearl Harbor and has been with us ever since.

The backlog of yard stock was exhausted years ago, and it will be many years

in the future before stocks can be built up at sawmills and distributing

yards for seasoning.

It is immediately advantageous to both the lumber producers and the

distributors to sell the stock unseasoned since it means quick turnover of

capital invested, reduced labor costs for piling and handling, reduced in-

surance and carryi-nr charges, and no loss in rrade that may accompany sea-

soning. Tlevertheless, the responsible sa-.rmill operators and lur'ber dealers

understand the disadvantages of using unseasoned lumber and would prefer to

sell it seasoned. On the other hand, the current demand for lumber of any

kind is imr.crative and leaves them no choice but to sell it as fast as it

can be produced. The ultimate ho o-.cmers are, however, generally unaware

of the hazards they will encounter az a result of usirq the lumber unsea-

soned.

The GI in need of a place to live is naturally impatient in his

demand for a home but also expects that the materials used are of good

quality and suitable for the purpose. He will be bitterly disillusioned

when he finds through defects that develop in the structure, that unseasoned

material has been used. We have been building houses since our ancestors

first landed in this country and have learned how to build better houses

than they built,but we still have not learned how to build good houses of

unseasoned lumber.

,Joodsused for construction materials are of two classes: (1) those

used for beams, joists, studs, raftors, sheathing, and subflooring, commonly

Report No. Rl113 -2-






called framing or yard lumber; and (2) those used for flooring, finish, trim,

doors, and windows, called finishinr lumber or planing-mill products; Iost

items of framing lumber are customarily air-dried for several months at the

mill or distributing yard. At present, however, a large part of the framing

lumber is shipped as soon as cut, and the distributors take it direct from

the freight car to the building site. Hence, it is nearly as green when

delivered as when cut from the tree. Finishing lumber goes from the savrmill

to remanufacturing plants where it is kiln-dried before it is mad: up into

finished products. The larger, well-equipped planing mills cannot supply

the demand for windows, doors, and interior finish, and plants not equipped

with adequate kilns are producing these items from inadequately seasoned

lumber.

When lumber dries, considerable shrinkage develops, and this shrinkage

should take place before rather than after the material is assembled in a

structure or finished article. Unequal shrinkage may cause the individual

pieces to warp or twist, to check and split. Good seasoning practice at the

mill minimizesthese defects,but there is no adequate means of controlling or

preventing such defects where unseasoned lumber is used in construction and

the seasoning takes place after erection.

Defects that can be expected to develop in conventional construction

resulting from the use of unseasoned framing lumber are principally the re-

sults of unequal shrinkage,which causes excessive and unsightly plaster

cracks, distortion of door and window openings, binding of moving parts,

doors that will not latch, openings and cracks that permit air infiltration,

and floors that are not level. Shrinkage around chimneys, fireplaces, and

plumbing pipes creates leaks and sometimes a fire hazard. Warping, twisting,
results in
checks, and splits also weaken the structure, and in some cases/distortion

Report No. Rl613 -3-






of roof or walls; nails driven into unseasoned lumber loosen up later when the

lumber dries. Unzeasoned lur.ber also adds a decay hazard, particularl- over

basemantlesz structures. $Shrin,:;e of irnadequately seasoned finish lumber

causes open niter joints in door and -vindow' casings and similar finish, and

cases doors and panels to warp and twist. Shrinkage of flooring causes open

cracks bot-een floor boards, creaking and noisy floors and stair treads.

Blue stain resent in exterior finish causes paint discoloration.

The defects naturally result in greatly increased maintenance costs,

disfigurement that cannot be concealed, ani dissatisfaction on the part of

the over with his investment. It may be expected that o-wners will not take

pride in such homes, but will attempt to sell or dispose of them just as

soon as better houses are available.

In producing prefabricated houses of wood the same necessity for sea-

soned material is equally important. The parts must have practically no

shrinkage from the time they are nachined and assembled in shops until they

are erected on the site; otherwise the units will not fit together properly.

Unseasoned material does not have such stability. The covering- parts of

prefabricated floors and walls are generally glued to the framinr members,

and strong glue joints cannot be obtained with unseasoned material.

The influence of powv-rful agencies, both Gov.-rrnmcnrtal and private,

will be required to get properly seasoned lumber back on the market again.

It is to the interest of all agencies financing building construction to in-

sist that the materials used be suitable for the purpose, and such agencies

can play an important part in establishing suitable moisture content specifi-

cations and adequate policing to obtain complin.ncc. It will also be necessary

to establish economic incentives by which it will be to the interest of manu-

facturers and dealers to distribute seasoned stock.

Report :-o. PRl613 -4-






Pending the time when seasoned stock is again available the individual

builders can help themselves by certain oey.pe diets that can be emr-loyed to

obtain some degree of seasoning before the building is plastered. For ex-

ample: (1) Purchase framing lumber as far in auvw.nce of actual construction

as possible and have it piled on stickers according to good piling practice.

Sixty days for inch lumber and 90 days for 2-inch lumber will generally

provide fairly well-seasoned stock. (2) Halting the construction after the

building is framed, sheathed,and roofed and before it is lathed will result
in comparratively rapid seasoning. It may. take 60 days, however, to dry the

stock to a well air-dried condition, (3) Since the vertical shrinkage of

joists and plates is cumulative, there will be more evidence of shrinkage in

the second floor than in the first floor of an all-frame house. On this

basis, one-story houses will suffer less than two-story houses and owners

might consider one-story houses wv;hen these can be made to suit their needs.

(4) In some localities dry kilns can be found where the owners are willing

to kiln dry stock for a fee. In a suitable kiln, framinr- lumber up to 2

inches thick can be adequately dried in about 1 week. (5) Ordor interior

finish and trim from companies that are adequately equip ed with dry kilns

orthat are in a position to obtain properly seasoned material.

Time and money expended to get dry lumber or to dry it before the

house is enclosed will pay good dividends in reducing maintenance, increas-
/ing the value, and satisfaction of ownership of the completed structure./
ing the value, and satisfaction of ownership of the completed structure.


Report No. R1613


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