A roofing material should not be judged by its first appearance, but
rather by its condition after four or five winters have passed over it.
And in choosing the roof for the small house, this is a statement which
applies with even greater emphasis, since the temptation is magnified
to select that material which is low in cost and bright upon its first
appearance.
As an illustration, there are certain types of wood-shingle roofs
which have a charm in the beginning that is apt to disappear with age.
These are constructed of shingles, dipped in many varieties of colored
creosote stains, browns, reds, greens, blues, yellows, and the like,
and when newly laid have a warm, mottled, and colorful texture which
suggests the multiplicity of tone that nature often produces with age.
In fact, the designer who originated this roof was trying to imitate
the aging effect of nature, much as Tiffany glass is an imitation of
the effect of time upon certain ancient glasses; only in the latter
case the operation is the same but the time element reduced, while in
the case of the roof it is a theatrical imitation of nature at work.
And there are many other fads in roofing, all of which have as their
basis the imitation of the weathering effect of nature. Ridge-poles
are constructed with a sag to resemble the settlement which is often
observed in picturesque old houses. Shingles are laid, like the scales
of an armadillo, and ridges, hips, and eaves are rounded to present
the appearance of old thatched roofs. Asbestos shingles are broken
with rough edges, and defective tiles are used—all for the purpose of
giving that ragged appearance which nature develops with age. Now, to
a certain extent there is an element of architectural truth in such
devices, but they should be used with the greatest discretion, for, as
has been previously asked: “If a roof looks old when it is new, how old
does it look when it really is old?”
Before discussing the various methods of laying roofing materials, let
us observe some of them after they have been on the house for a few
years.
Of course, we are all familiar with the short life of the wooden
shingle, which is only about fifteen years. But the life can be
extended by dipping them into creosote stains, either just before
laying or by the more convenient processes of factory dipping. Cedar
has been found to be the best wood for these shingles, since it has
a natural resistance to decay. The old hand-split shingles were more
durable than the modern shingles, for the surface that they exposed
to the weather was the natural cleavage plane of the wood fibres. The
sawed shingle delights in curling and twisting out of a flat plane, and
always seems to split so that the crack lines up with the space between
the shingles on the course above, thus permitting the rain to leak
through. And then the nails either rust away or the wood rots around
them, until individual shingles drop away from the others, leaving
small or large holes in the roof. It is well recognized that the sparks
from a neighboring fire find a ready meal in the punk and rotten butts
of the shingles, and many a house has been burned to the ground because
of this.
The nearest competitor to the wooden shingle in cost is the asphalt
shingle, which is made from roofing felt, saturated with asphalt
compounds, and surfaced, under pressure, with crushed slate of greenish
or red hue. The life of these shingles depends a great deal upon
the thickness of the body. Some roofs, laid with very thin asphalt
shingles, develop an appearance of chicken-pox after a year or two,
for the heating effect of the sun, the lifting force of the wind and
ice cause certain individual shingles to bend up from the plane of the
roof and, in extreme cases, even flap in a heavy gale, like so many
small pin-feathers. But this is not so true of the thicker grades of
these shingles. Often, too, these asphalt shingles bulge under the hot
sun, but this is due to careless laying, for each shingle should be
separated from the other by a small space to allow for this expansion.
It takes a good many years for the crushed slate on the surface to
wear off, but gradually this happens, as also the elasticity of the
body degenerates. Finally, as the surface begins to moult, the shingle
itself becomes stiff and brittle and begins to break off. Of course,
these shingles are superior to wood in resisting sparks from a near-by
fire, and their life is longer, if they have a thick enough body.
That same material used for asphalt shingles is made into roll
roofings. So-called shingle strips are made, which consist of long,
narrow rolls of asphalted felt with the crushed slate surface, the
lower edge of which is cut out to form the lower third of the shingles,
and, when applied to the roof, the appearance is identical to a roof
laid with individual units. Another type of roll roofing is made to
imitate wood shingles, by having a shingle pattern stamped with black
asphalt upon the surface of crushed slate. It is laid on the roof from
the ridge down to the eaves, lapping joints with the next roll about
two inches. At a distance the black pattern gives the camouflaged
appearance of a shingle roof. The chief objection to any of these roofs
is that the long and large areas are nailed down along the edges so
that the sag and expansion of the material raises little bumps and
hills over the entire roof, which, to say the least, is very unsightly.
Then, again, the nails are exposed, and unless they are copper, the
chances are that they will rust away before the roof is worn out,
permitting the edges to become loose and the wind to get under the
material and rip it away from the roof. Moreover, the roll roofing has
only one thickness at any point, while the shingle roofing has either
two or three layers over the entire area of the roof.
The cheaper grades of slate roof, such as one would be tempted to use
on the small house, show weaknesses in aging that should not be used as
arguments against slate roofs in general. These cheap roofs are built
up of poorer grades of slate, and very thin sheets at that, and a poor
grade of nail is used. The effect of weathering on such roofs is to
chip off pieces of slate and to rust the nails, so that whole units
drop off. Generally, too, in these cheap slate roofs, the tar paper is
omitted from underneath, and the wind suction through the roof draws
the snow through the cracks onto the floor of the attic, where it melts
and stains the ceilings below. However, properly selected and well-laid
slate roofs have none of these disadvantages, but then the cost of them
is generally a barrier to using them on the small house.
As with the slate roof, so with the tile roof, the cost is generally
the reason for not selecting it, and yet, from an economical point of
view, in the end they are not as expensive, since with the less durable
roofs one is never sure of how much damage to the interior a leak will
cause. Tile roofs of poor quality have as bad reputations as slate
roofs. Small, thin tile are very brittle, and falling limbs and other
objects often break individual tiles, and it is very hard to replace
them. Unless the tile are laid upon a building-paper the wind suction
is even worse than with slate roofs.
Probably the greatest defects in tile or slate roofs is not in the
material itself, but in the flashings and valley construction. Instead
of using copper the flashings are usually of tin, which is permitted to
rust out because of neglect in painting. Leaks develop in the valleys
and around chimneys in spite of the roofing material.
While asbestos shingles can show great practical durability, even
superior to slate and tile in some cases, yet there are many instances
of ugly weathering. Tile and slate roofs develop warm, lovely tones
with age. Asbestos shingles, since they are chiefly made from cement
under pressure, must necessarily depend for their color upon inert
pigments introduced into their composition at the time of manufacture,
and for this reason their color is apt rather to fade than become
richer with age. Their tendency is to return to the natural color of
the cement. For this reason we see on every hand red asbestos shingle
roofs which have bleached out to sickly and thirsty pinks, and brown
roofs that have blanched to whitish-brown, much like the color which
chocolate candy develops when it is very stale. Then, too, certain
makes of asbestos shingles show, as time goes on, salt-like deposits on
the surface, like the whitewash which appears upon brick walls. This
gives a motley appearance to the roof, for some shingles will develop
this white stain more than others.
The reader should not draw from these statements the general conclusion
that the asbestos shingles should not be used, and that there have been
none made that overcome the above difficulties, but it would be well
for him to observe these defects before deciding upon any one brand.
The manufacturers of tin advise that the tin be painted on both sides
when laid, and thereafter kept painted at four to five-year intervals.
In other words, the tin roof is as good-looking as the paint which
covers it, for it has no color or texture of its own. Can there be much
charm in a roof of this kind? Can one picture a cosey and homelike
small house with either a flat or standing seam tin roof? Perhaps the
flat decks which do not show are satisfactory, when covered with tin,
but those upon which any walking is to be done should be covered with
wood lattice or else the nails of the shoes may punch through the tin
and cause a leak. Tin roofs have their place and their duty to perform,
but they are hardly suited to flat roofs over which is to be done much
walking. Heavy deck canvas, laid in paint and covered with paint,
is the best for this purpose. The ferry-boats give evidence of the
practical wear of this kind of roof.
Tin or galvanized-iron shingles or imitation tiles are often seen
applied to the roofs of small houses. The owner probably admired a real
tile roof, and the nearest approach his pocketbook would permit him to
come to it was the use of imitation tile of tin, copper, or galvanized
iron. Most architects ridicule this peculiar weakness in human nature
which chooses imitation diamonds, glass pearls, oil-paper stained-glass
windows, and pressed-metal tiles, instead of real ones, but they should
look to themselves before they throw stones, and ask who invented the
imitation thatched roof of wooden shingles.
_Shingle Roof_
The wooden-shingle roof is of such old and traditional origin in this
country that it seems useless to describe the essential features of its
construction, yet for the sake of completeness we shall call attention
to the important points to be observed. Cypress, cedar, and redwood
are considered to be the best woods from which to saw shingles. The
grain of the wood should be vertical and show the edge. It is generally
conceded that creosote-dipped shingles which are treated at the
factory are easier to apply than those dipped on the job, and, as all
wood shingles should be treated with some preservative, it is well to
consider them. However, much criticism has been aimed at factory-dipped
shingles, in that they are generally too brittle from overdrying in the
kilns, but this is not true of all makes. The sizes and the weathering
of some of the standard creosoted shingles are as follows:
16 inches lengths, random widths, laid 4½ inches to
the weather, and either 5 or 6 shingles at the
butt ends to 2 inches.
18 inches lengths, random widths, laid 5½ inches to
the weather, and 5 butt ends to 2½ inches.
24 inches lengths, random widths, laid 7½ inches to
the weather, and ½ inch thick at the butt ends.
There are about thirty varieties of colored stains to select from, and
special shapes are cut for constructing the so-called thatched roof,
the shingles being bent to a curve of about 20 inches radius. The pitch
of wooden-shingle roofs should not be less than 8 inches rise per foot
for the ordinary weathering shown in the above statements. The tops of
rafters are covered with shingle lath, with a spacing suitable to the
weathering arrangement of the shingles. There are some who advocate
the use of sheathing to cover the rafters in a tight manner and also
the use of building-paper underneath the shingles, but, although this
gives a tighter and warmer roof, dry rot attacks the shingle much
quicker because of the accumulation of dampness on the under side of
the shingle courses.
The first course of shingles at the eaves should be a double course
with the upper layer breaking joints with the lower, and the shingles
should project about 2 inches beyond the mouldings of the eaves and
about 1½ inches beyond the edge of the gable ends of the roof.
Hips may be finished either with the saddle-board or with a row of
shingles running parallel to the line of the ridge. Hips are best
finished with a row of shingles running parallel with their edges,
which treatment is called the Boston hip. If the courses are carried
to the hip line and mitred, then the joint must be waterproofed by
using tin shingles underneath the wooden ones, these tin shingles
being folded over the hip. The method of flashing around chimneys, at
the base of dormers, and in open valleys will be more fully discussed
in connection with slate roofs, and, since the principles are the
same, what is said for slate roofs in this connection is true for
wooden-shingle roofs.
_Method of Laying Roofs_