| 摘要 |
<p>A tile (10,120) is formed from a relatively thin sheet adapted to cooperate with similar tiles to form a tiled surface. When the tile is installed, the central axis (12,125) thereof coincides with a line defining free water flow down the tile between upper and lower tile portions (14,15). The tile has first and second raised ribs (45,46; 131,132) extending symmetrically as mirror images of each other on each side of central axis. Each rib has upper (49,51) and lower rib (50,52) portions which are interconnected so as to extend continuously between the upper and lower tile portions to increase stiffness of the tile. The stiffened tile is better able to resist weight of a person walking on the roof, and also resists a tendency for the lower portion of the tile to lift when wind blows onto the roof. The upper rib portions (49,51) are generally complementary to the lower rib portions (50,52) so that the lower rib portions of an upper tile can fit over upper rib portions of a lower tile. Thus rib axes (47,48) of upper and lower rib portions are also mirror images of each other about a lateral axis (27,127) disposed perpendicularly to the longitudinal axis (12,125). When the tiles fitted, the ribs of the tiles are interlocked and this increases accuracy of installation of the tiles, as well as reducing a tendency of water seepage past edges of the tiles. The tiles exhibit a high degree of fitting tolerance, even when fitted on an uneven roof, thus permitting use of relatively unskilled labour.</p> |
