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 pocket-book 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.