A gutter tile has come into use in England ; it forms the lower course, overhangs the lower sheathing-board or lath, and is nailed to it.
Sliding tiles are used as substitutes for weatherboarding; holes are made in them during moulding, and they are secured by flat-headed nails to the lath.
The exposed face, called the gauge, is sometimes indented to represent courses of brick ; fine lime mortar is introduced between them, when they rest one upon the other.
These sliding tiles are sometimes called weather-tiles, and sometimes mathematical-tiles, the names being derived from their exposure or marking. They have a variety of forms. having curved or crenated edges, and are also variously orna mented with raised or encaustic figures.
Modifications of the pantiles are shown in the examples a b, Fig. 230, the edges being turned up and down respectively ; c de are modifications of the ridge-tiles, in which the gutter and ridge are placed alternately. f g show modes of securing; the first is moulded with a lug, which secures itself in position by catching above the lath of the roof ; the second shows a tile moulded with two lugs, by which it engages the tiles of the courses above and below.
h, h' ,h" are elevation, section, and perspective views of a tile exposing a semicircular face to the weather. The semicircular portion has a drop flange, which catches over re-entering curves of the upper part, these curves having upturned flanges for that purpose. Whenever roof-tiles are to be glazed, they are var nished after being burned ; the glaze is then put on, and the tiles are then placed in a potter's oven and remain until the glaze commences to run. The glaze is usually made from what are called lead ashes, being lead melted and stirred with a ladle till it is reduced to ashes or dross, which is then sifted, and the refuse ground on a stone and re-sifted. This is mixed with pounded calcined flints.
A glaze of manganese is also sometimes employed, which gives a smoke-brown color.
For a black color iron filings are sometimes used ; for green, copper slag; and for blue, smalt is employed, the tile first wetted, and the composition laid on from a sieve.
At one time very inferior roof-riles were made in England on account of the careless weathering or preparation of the clay employed ; and in order to cure this a statute of Edward IV. required that all clay for tiles should be dug, or cast up, before the first of November, and not made into tiles before the March following.
The garden of the Louvre in Paris was called the Tuileries, as being a place where tiles were anciently made; a magnifi cent palace was begun there in 1564 by Catharine de Medicis, wife of Henry II., finished by Henry IV., and splendidly by Louis XIV., but was sadly defaced in our times, during the Commune of 1871.
Modern tile-covered roofs add greatly to the picturesque ap pearance of buildings.
A portion of a roof covered with diamond shaped tiles is shown in Fig. 231, and the form of the tile is shown in a sec tion, and a plan of face and bed.
Fig. 232 shows a roof covered with tiles of various shapes, and Fig. 233 shows the six forms of roofing tiles in most com mon use in this country.
A great advantage for the tile roof is that it is a non-conduc tor, and, therefore, cooler in the summer season than any other kind of roof. The buff tile, being lighter in color, is the cool est, as it does not absorb the rays of the sun. Tiles are also a better protection against lightning than the lightning-rod, as the latter attracts electricity, while the former is a non-conduc tor. Insulators, made of pottery, are extensively used on tele graph lines in Europe and portions of America.
The rain-water collected from a tile roof is much purer and cleaner than from any other kind of roof, as the tiles are very smooth, and no dust or soot settles upon them.
Tiles are indestructible, and are not affected by heat or cold, They will not crack and slide off the roof, like slate, leaving the sheathing exposed, when subjected to sudden heat, as by the burning of an adjoining building.
After doing service on one structure, the tile can be taken off and used on other buildings. Tiles should not be put upon a roof that has less than one-quarter pitch (a slant of six inches to the foot), although we have seen some roofs of less pitch which were satisfactory. A roof to support tile should be some what stronger than for shingles. The rafters should be 2x6, 18 inches apart, and well-stayed, so that they cannot spread. The sheathing should be of soft wood, of even thickness, and close together. Generally felt or tarred paper is placed under the tile, although it is not necessary to make the roof water-tight, but it stops circulation, and makes the roof warmer in winter, and adds but little to the cost.