| 摘要 |
Both right-hand and left-hand valley slabs for covering over a valley between two intersecting, rising roof surfaces can be obtained from a single embodiment of a valley-slab blank. Such a valley-slab blank comprises a planar slab material with a predetermined outer surface and has an outline which is delimited by a straight, sharp edge (slab front) and by a slab back which is aligned essentially parallel thereto and is arranged at a distance therefrom, and by two connecting edges which connect the shorter slab back to the longer slab front. One connecting edge runs - with respect to a central plane perpendicular to the longitudinal axis of the blank - in a mirror-inverted manner with respect to the other connecting edge. Preferably, each connecting edge follows essentially a hyperbola branch, whose curved portion merges into the slab back and whose largely straight portion intersects the slab front.
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