Group Title: Historic St. Augustine: Block 10 – Lot 1
Title: Terneplate (Metal Roofing)
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 Material Information
Title: Terneplate (Metal Roofing)
Series Title: Historic St. Augustine: Block 10 – Lot 1
Physical Description: Maintenance record
Language: English
Copyright Date: Public Domain
Physical Location:
Box: 4
Divider: B10 L1 - Dr. Peck History
Folder: Block 10 Charlotte St.
Subject: Saint Augustine (Fla.)
143 Saint George Street (Saint Augustine, Fla.)
Dr. Peck House (Saint Augustine, Fla.)
Peña-Peck House (Saint Augustine, Fla.)
Spatial Coverage: North America -- United States of America -- Florida -- Saint Johns -- Saint Augustine -- 143 Saint George Street
Coordinates: 29.893507 x -81.312774
 Record Information
Bibliographic ID: UF00094115
Volume ID: VID00081
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: B10-L1

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Physical and Chemical Properties

Terneplate is dull gray in color, lightweight and strong. It

originally consisted of sheets or strips of iron in two grades,

coke iron and charcoal iron, coated with a lead-tin alloy. Later

steel was used. Today terneplate is usually a 28 or 30 gauge

steel alloy (low carbon steel with or without 0,2% copper) with a

hot-dipped coating of an alloy of lead and 10% to 25% tin. In

this country rimmed, capped or aluminum-killed steel sheet is the

commonly used metal. For roofing, the copper content of 0.2% is

recommended to increase the corrosion resistance of the steel,

Base Weight. Terneplate, like tinplate, is produced to a

base weight expressed in pounds per base box. In other words,

the weight of a coating refers to the total weight of terne metal

distributed on both sides of 112 sheets, 14" X 20" in size (or an

area equal of 217.78 sq. ft.). Sometimes the weight is given per

double base box (112 sheets 20" X 28" in size).

Expansion Rate. Terneplate has a slight expansion rate of

only 0.825" per 100 ft. per 100oF, change in temperature. This

low rate of expansion means that runs of 30'-0" can be made with-

out expansion joints.

Chemical Reactivity. Terneplate reacts with acids and alu-

minum. In fact, its reactivity with contacting materials parallels

the chemical reactivity of lead and tin. Lead and .tin act as

cathodes to iron and may accelerate corrosion at pinholes if they

exist. Heavy-coated sheet has no pinholes but should be painted.

Terneplate is usually given a shop coat of paint on both sides,

but painting after installation is also necessary.


Types and Uses

There are two grades of terneplate, short terne and

long ternes

Short terne. This type comes in sheets and 50-ft. rolls.

It has a coating of 20 to 40 lbs. per 112 sheets of 20" X 28"

(10 to 20 lbs. per single base box unit) on 28 to 30 gauge

copper-bearing steel alloys. The coating consists usually of

85% lead and 15% tin. This grade is generally used for roofing,

flashing, gutters and leaders (see Table T5).

Table T5 Standard Sizes of 28 and 30 Gauge
Short Terneplate

Width Sheet Roll
14 l'-8" and 8'-0" 50
20 2'-4" and 8'-0" 50
24 8'-0" 50
28 8'-0" and 10'-0" 50

Long terne. This is a sheet mill product which comes in

rolls up to 90' in length and in cut lengths in large sizes up

to 4'-0" X 10'-0". It has a coating of 8 to 40 lbs. per 112

sheets of 14" X 20" on 30 to 14 gauge (maximum) metal. The

coating consists of 872 to 80% lead and 121 to 20% tin. Long

terne is used for gasoline tanks, automobile body parts, doors

and frames, and other fireproof construction as well as for

roofing. For doors and frames and fireproof construction, the

gauge and weight of coating are set by the National Board of

Fire Underwriters.


History and Manufacture

Terneplate originated in Wales about 1700, although at that

date it was known as tin roofing. Its use in the United States

became.widespread in the early 19th century. One example, Andrew

Jackson's home, The Hermitage, still has a terne roof which was

installed in 1835.

Terneplate is manufactured by a process similar to the zinc

galvanizing process. The metal to be coated is pickled, passed

first through a weak solution of hydrochloric (or sulfuric) acid

and then through a heated solution of zinc chloride (or zinc

chloride plus hydrochloric acid), which acts as a flux for better

adhesion of the coating. From here the metal is passed into a

molten lead-tin alloy which is kept at about 7000F. to 7250F.

and covered with palm oil to prevent oxidation. As the metal

sheet emerges, it passes between rollers which remove excess

metal and oil and give a smooth coating. The sheet is then cleaned

with flannel disk rolls and brushes, using sawdust, bran or

similar absorbent to eliminate the oil.

Materials for Architecture; Caleb Hornbostel; Reinhold Book
Corporation, New York

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