Scale roofing is primarily used for curved surfaces such as church domes or bell towers. The installation, in these cases, necessarily involves the use of nails and/or lime. The construction of dome coverings starts from the bottom with slate battens that decrease in size as you ascend and the diameter of the dome decreases. The installation of each batten also involves tapering the individual slates upwards to allow for side-by-side placement. Consequently, covering a dome is a highly demanding operation that requires the dedication of skilled workers. The semicircular curvature at the bottom of the slate facilitates placement on the curved surface.