| 摘要 |
The lightweight corrugated roofing material, e.g. of a bitumen-impregnated cellulose material, a plastic such as PVC or of steel, is designed to be used on its own or as a support for flat or channelled tiles, and has corrugations (2) with transverse recesses (3) at intervals for the tiles to engage with. The amplitude and pitch of the corrugations are in a ratio of between 1 : 1 and 1 : 2, and the upper surfaces of their crests, which are slightly flattened, are roughened, having projections between 0.1 and 0.9 mm high and at a rate of between 1 and 100 per sq cm. |
