TESTING VULCANITE ROOFS.

TESTING VULCANITE ROOFS.

The question of a fire resisting roof is one which has long exercised, and still continues to exercise the minds of architects and builders. An ordinary slate roof has no pretensions that way; tin is an acknowledged failure; gravel is by no means infallible; and where the accustomed red tile is used success is by no means a certainty. Into these considerations, of course, the new style of fireproof roof as practised today does not enter. Such buildings are not in common use for other than business, manufacturing, hotel, large apartment, or assembly room and theatre purposes. What is wanted is a fire-resisting roof for the ordinary dwelling or the smaller stores.

对获得必要的知识subject the British Fire Prevention committee has been experimenting as to what style of roof will best withstand a fierce fire of one hour, beginning at a temperature of 500 degrees Fahr., gradually increasing to 1,500 degrees, followed by the application of a stream of water for three minutes. The superficial area covered by each roof experimented upon was about 100 square feet; the time allowed for construction (the work being done in spring) was about four weeks. The slated roof was constructed of deal. The wall-plates were four and onehalf inches by three inches; rafters, five inches by two inches; ridge, nine inches by one and one-half inches; ceiling joists, four inches by two inches; slate battens, two inches by three-quarters of an inch; gutter boards, one inch thick; and bearers, one inch by three inches. The roof was covered with American green slates, twenty inches by ten inches, and three-sixteenths of an inch thick, with a two and a half-inch lap, and each slate was nailed by two zinc nails. The ridge was covered with blue Staffordshire ridging. The laths were sawn sprucelaths one and one-quarter-inch by one-quarter-inch The first coat of plastering consisted of coarse stuff composed of lime and sand in the proportion of 1 to 3, mixed with a proportion of hair, and a small admixture of plaster of Paris (1 in 16). Th.e second coat was of the same material, finished fair; the total thickness of plastering was about one inch. The gutters were lined with No. 14 gauge (Vielle Mnntagne) zinc. After the ceiling was completed a salamander was lighted in the chamber, for one day. to assist in drying the plaster. The Vulcanite roof was also of deal. Its wall-plates were four and onhalf inches by three inches; joists, seven inches bv two and one-half inches; boarding to flat, one and one-quarter inch thick in four-inch widths, grooved for iron tongues. The hoop-iron tongue was seven eights-inch wide; the angle fillet, four and one-half, inches by three inches. The Vulcanite roof covering consisted of asphalted felt in three thicknesses, laid to break joint, cemented together with a composition termed “Vulcanite,” which was brought to a plastic state by being heated in a cauldron and applied to the asphalted felt with a brush. The edge^ were turned up against the angle fillet and covered with a zinc flashing of No. 14 gauge (Vieille Montagne) zinc. The top of the vulcanite roofing was covered with a layer of gravel and sand two and one-half inches thick. The laths were sawn sprucelaths one and one-quarter-inch by one-quarter-inch. The first coat of plastering consisted of coarse stuff composed of lime and sand in the proportion of 1 to 3. mixed with a proportion of hair and a small admixture of plaster of Paris (1 in 16). The second coat was of the same material, finished fair; the total thickness of plastering was about one inch. After the ceiling was completed, a salamander was lighted in the chamber, for one day, to assist in drying the plaster. The roofs were then covered with tarpaulins for twenty-five days.