| 摘要 |
<p>A roofing element is described which comprises two spaced skins, an upper skin of relatively thick non-metallic sheet material, such as plywood or chip board, and a lower skin of sheet metal, for resisting compression stresses in the upper skin and tension stresses in the lower skin. The skins are bonded to spacing members extending in the lengthwise direction of the element and provided by composite beams of non-metallic or substantially non-metallic material, having webs of wood-based board material and flange members of wood. The spaces between the skins are filled up with a thermally insulating material, such as mineral wool or foamed uretane plastic.</p> |
