construction materials for the roofs of buildings and structures. Roofing materials must satisfy technical requirements (impermeability, weather-resistance, frost-resistance, and low combustibility) and economic requirements (low cost of the material and the installation of the base upon which it rests; ease of installation). Roofing materials may be organic (bituminous, tar, wood, and polymeric materials), silicate (asbestos cement and tile), or metal (roofing iron). They may be of the roll, mastic, or piece type (sheets or slabs).
Roll roofing materials based on bitumen (Ruberoid, per-gamyn, and glass Ruberoid) and tar (tar paper) are most commonly used. Roll roofing materials are relatively inexpensive and easy to install, and they provide a light and thin roof covering on almost any type of roof. Bituminous roll materials last for ten to 15 years; tar-based materials are good for no more than five to six years (tar materials are generally used for temporary structures). Tar-based roll materials have greater biological resistance than bituminous materials. Gidroizol (bitumen-impregnated sheet asbestos) and izol (a rubber-bituminous material reinforced with asbestos fiber) may be used as roofing materials in certain instances.
Mastic roofing materials are bituminous and tar roofing materials modified by polymers and used as independent materials for the installation of seamless roofing. A reinforcing element (glass cloth) is added to mastic coatings to increase cracking resistance. Mastic roofing materials are cheaper and easier to install than roll materials.
Piece roofing materials include roofing iron, artificial stone (mainly asbestos-cement), wood, and polymeric materials. Sheet roofing iron, particularly ungalvanized steel, requires frequent painting with expensive drying oils for corrosion protection, and therefore its use is decreasing. The most widely used artificial stone roofing materials are corrugated and semicorrugated asbestos-cement sheets and, to a lesser extent, flat slabs or tiles. Asbestos-cement roofing materials are long-lasting and easy to install, and they do not require periodic painting. Tile—mainly clay tile, and sometimes cement-sand tile—is a durable but heavy material, which requires a large quantity of wood for lathwork and rafter structures. Large corrugated sheets made of slag sitals and glass, which are noted for their high chemical resistance and durability, are widely used for the roofing of industrial buildings. Piece wood roofing materials (roofing boards, shingles, and chips) are useful only as a locally available material for agricultural construction in regions where wood is plentiful; they are also used in restoration work.
Piece polymeric roofing materials include flat and corrugated sheets made of glass-fiber-reinforced plastic and organic glass (Plexiglas), which provide transparent and semitransparent coverings.
REFERENCESVorob’ev, V. A., and A. G. Komar. Stroitel’nye materialy. Moscow, 1971.
Gidroizoliatsionnye, krovel’nye i germetiziruiushchie materialy. Moscow, 1963.
Stroitel’nye normy i pravila, part 1, sec. V, chap. 25. Krovel’nye gidroizoliatsionnye i paroizoliatsionnye materialy na organicheskikh viazhushchikh. Moscow, 1966.
K. N. POPOV