As the plastering of walls and ceilings usually gives, by cracking, the first indication of settlement, shrinkage, or decay in a house, so it also commonly reveals, by stains, the leaks in roofs, or around windows and skylights, which constitute, perhaps, the most distressing, because most unaccountable, troubles of the householder. The best of all roofs is one covered with the plain "shingle" tiles so universally used in Europe. For the American climate, with its violent winds, drifting snow-storms, and intense frosts, often following a warm rain, the tiles should be hard-burned, or " brown," as they are called in England, and laid in cement; and, as the tiles are heavy, comparatively strong rafters are needed to support them; but such a roof, with copper flashings where necessary, will often endure for centuries, and is practically fire-proof. Slate roofs, which also rank as fire-proof, are very inferior to those covered with tiles. The slates are brittle, and, as they are nailed, instead of being hung, like tiles, to strips laid on the roof, it is difficult to nail them tightly enough to prevent them from shaking in high winds, and breaking off at the nail without driving the nails occasionally a little too tightly, and breaking the slate in this way. In either case, a slate broken at a nail hole causes a leak, and there are few slate roofs which can endure a winter's storms without some breakage. Shingles are not disposed to break by shaking in the wind, or by being nailed too tightly, and form, so long as they last, a much better roof than slates; but they soon rot in the "valleys," or angles between intersecting portions of the roof; and inferior shingles may split or curl in the sun, also causing leaks.

Tile roofs.

Slate roofs holes.

Where the pitch, or angle with the horizontal, of any roof covered with shingles, slates, or tiles is too low, drifting snow will blow up under them, unless they are laid in cement, and melt there, often causing a small leak; and the shingles on low-pitched roofs soon rot out on account of the slowness with which rain-water drains away from them. The minimum pitch for such roofs should be 26 1/2 degrees, or "quarter-pitch," as the carpenters call it, the rise of the roof being one-fourth of the span, and a higher pitch is much to be preferred; and, unless the pitch is very steep, shingles, or slates, or tiles, should be put on over two layers of waterproof felt, tacked to the roof-boarding.

For covering flat roofs, such as are commonly found in city houses, and often in those in the country, copper, tin, or composition may be used. A copper roof is very costly, but, if not injured by walking over it, will last a lifetime. Tin roofs do well inland, but are not very durable near the sea, and they must be kept well painted to preserve them. Composition roofs, made with tarred felt, in two, three, four, or five layers, mopped with melted tar, and covered with gravel, are cheap, and good while they last, and are easily renewed.

Shingle roofs.

Pitch of roofs.

Flat roofs.

It is obvious that neither slates nor shingles will fit water-tight against each other, or against chimneys or walls; and, to protect junctions of this sort, flashings are used, consisting of strips or pieces of lead, zinc, tin, or copper, the general principle of their application being that the lower edge laps over the roofing, so as to throw rain-water safely away from the joint, while the upper edge is inserted tightly into a groove in the wall or chimney, so that water running over the surface of the latter will continue down over the metal, and will be thrown out upon the roofing; or, in the case of flashings in valleys, the strips or pieces of metal are so arranged as to receive the rain-water flowing down over the slates or shingles on each side of the valley, and conduct it to the gutter. In practice, however, flashings, to save metal, are usually made too narrow, so that water, in heavy rains, overflows them, and runs into the rooms below. In the case of chimney flashings, the metal often warps out of its groove, so that the water runs down behind it; and zinc or tin flashings in valleys in time corrode, and allow the water which runs down the valley in storms to escape into the house, causing a very bad leak.

Flashings.

An examination of the wet spot in the plastering caused by a leak in the roof will generally indicate the source of the trouble. If it is near a chimney, or, in a city house, near either a chimney or a brick wall, or in the neighborhood of a skylight or scuttle, it is probably due to defective or too narrow flashing at that point. If, in a house with a pitch roof, with intersections of dormers or other roofs, it appears under a valley, it is probably due to the deficiency, corrosion, or displacement of the valley flashing, or to the rotting of the shingles in the valley. If the roof is flat, and the wet spot is large, and is not near a wall, chimney, or skylight, it probably comes from defects in the roofing itself, such as holes in a tin roof, caused by corrosion, or by walking over it, or shovelling snow from it, or, in a composition roof, from dry, spongy places, due to the long-continued action of the weather. Such leaks in tin roofs can be mended with a drop of solder. Leaks in composition roofs may sometimes be patched, but roofing of this kind does not often show defects until it is so extensively decayed as to need entire renewal.

Minor wet spots in plastering often occur, after heavy rains, from other causes than leaks in the roof. Gutters are not infrequently so arranged that, if choked with leaves or ice, they overflow into the house; and it often happens in winter that snow and ice freeze to the lower edge of a roof, where it projects beyond the walls, and is thus out of reach of the warm air of the house, and the border of ice thus formed around the roof intercepts the water descending from the melting of snow lying on the warmer portions of the roof above, and causes it to back up under the shingles or slates until it finds its way into the inside of the house. Windows, also, in wooden houses, are vulnerable features, and, unless the top of the upper outside casing is protected with sheet lead, as it always should be, but often is not, water will drive in during heavy rains, and show itself inside at the edges of the casings, or will drip through the top of the frame, and stain the curtains and shades; while the rain-water which runs over the glass, collecting on the outer sill, will often blow through to the inside, staining the plastering or paper beneath the window.

From whatever cause they proceed, wet spots in plastering indicate defects which should be attended to immediately, to prevent further damage. Flashings, broken slates, and rotten shingles can only be attended to by a roofer or carpenter, and the roofer employed for the purpose should be thoroughly reliable, as it is a common trick among the inferior ones, when employed to make repairs, to loosen sound flashings, or break good slates, so that they may have another c job when the next rain-storm comes. The trifling leaks which occur around windows in driving storms can generally be cured with paint, mixed thick, and pushed into the crevices with a putty-knife, or with thin sheet lead, tacked on where necessary.

Repairs.