The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1843-02-05
Metal Roofing.

MIR. EDITOR
My attention has recently been attracted TO
this subject by observing that the new church in
Broadway Is being covered with sheet copper. Ma
ny advantages accompany a metal roofing, but
where economy and the absence of weight in the
ROOT are important, then tin plates covered with
zinc, or as they are termed, galvanized, are yerv
greatly preferable to copper ; and if the plates be
properly united and carefully laid they are at least
as durable.
Economy in richly endowed church NAV moi he
matter of moment, as every part of the structure
from the foundation upwards, may be massive bur
in most other edifices particularly wide and ele
waited buildings, such as public institutions, manu-
factories warehouses, theatres, and private resIden
ces generally, economy originating in light, cheap
and durable roofing, is point OF the very first
slderation.
A light roof admits of less ponderous, and there
fore of less costly materials in building, in all the
varied combinations OF wood, iron and brick work,
without impairng the general strength and solidiy
Now, ahhundred square feet of copper roofing
weighs about l25 lbs, whereas the same extent of
tin plate, zlnced, does not weigh than from IS
to lbs Here, then. is difference of more than
80 per cent in weight against copper; and to
price, it costs about five times as much tin plates
zinced, independently OF the additional expense of
much more solid materials throughout.
If the advantages of this kind OF roofing bet
ter understood, and more universally known, few
would have their premises covered with any other
substance. Zinc alone has frequently been used for
this purpose, but it is incapable of the contraction
and expansion which the extremes of Temperature
in this climate submit it to. Iron, on the contrary,
is not injuriousy affected by these sudden changes;
the only point therefore is to protect from corro-
sion.
This is effectively accomplished by covering il
with zinc but much more effectively accomplished
when the sheet iron is first covered with tin, and
then with zinc, because both these metals are pro-
tectors The TIN enters into every PORE and sheathes
every atom of the iron, which no electric action
can reach as long as the tin exists, whilst the zinc
protects both
If no other metal be brought into contact OUT
wardy with the surface of the zinc, this species Of
roofing will remain unlmpared for long series of
years. This fact will show those persons engaged
in this sort Of business the necessity of fastening
all such roofing, flooring, CUTTERS spOuts pipes, &c.
with zinc nails and in all solderngs the sides of the
plates should be laid flat upon each Other with the
solder between or underneath, so that it may be as
little exposed possible to the action of the atmos-
sphere. The mode of tapping and hammering the
lolnngs as now practsed, render the superficial me-
tallc coverings thinner and the solder when run
always productive of decomposition. To prevent
this effectively, the seams should be covered with
paint made OF the oxide of zinc, and then the whole
surface is homogeneous, and no such action super
venes. II two metals arc brought into contact, and
their surfaces exposed 10 the atmosphere, the
sion of the most oxidizable is inevitable
have been informed, perhaps enormously, that
the copper roofing on the new church in Broadway
is soldered, and fastened with iron nails If this
be fact, then the whole of that roof is extern
slve gavanle battery, where the copper is acting
upon both the nails and the solder, which will be
destroyed within very moderate PERIOD not only
from atmospheric action, but from the thousands of
nails being constantly stimulated by the pyr0lig-
acetic acid sap and wafer contained in the
imbers, into which they are driven. Yours, respect
fully, W. A. KENrIsB
NEW YORK, Jan. q, 1913.