In most cases a waterproof membrane, such as a layer of asphalt, several coats of a tar or bitumen substance, or polythene sheeting is laid under the floor to prevent dampness rising through the concrete from the ground below.

• 大多数情况下,都要在地面下面铺防水层,诸如涂一层地沥青,多层焦油沥青或沥青质材料,或聚乙烯薄膜,以防止地下的潮气透过混凝土上升。