| 摘要 |
<p>The weighting layer is of the type provided on loosely laid flat roofs, usually in the form of shingle, which may be locally difficult to obtain, or unsuitable in strong winds. A prefabricated square sheathing is used, with an inserted filling of fluid or heaped material, such as sand or water. It may be open, in a trough shape, with a grating or other covering which can be walked on. There can be connecting elements for abutting square sheaths on two adjacent sides. It can be made of plastic.</p> |
