| 摘要 |
A roof covering of shingles or tiles is provided, with each shingle or tile being relatively rigid, having relatively flexible stress relief nail zones, that may comprise variations in thickness relative to the remainder of the shingle or tile, or variations in materials, such as will allow for relative movement of the shingles or tiles due to temperature variations resulting in expansion or contraction, or due to other forces, such that the movement will be between the shingles or the tiles and the nails or other fasteners that are used to secure the shingles or tiles to a roof or other surface, and is preferably within the elastic limits of the fastening zones of the shingles or tiles. |
