Interlocking benefits
Clay tiles with interlocking interlocking joints, with raised sliding surfaces or with a flat roof.

Whereas flat tiles, like canal tiles, only overlap, providing a watertight seal for a third of their surface area, this interlocking tile used three-quarters of its surface area. In these conditions, this interlocking process, by limiting overlaps, considerably reduced the weight of the roofing: thirteen of these interlocking tiles were enough to cover 1 m ² of roof, whereas with plain tiles, around sixty were needed.

Another advantage of these interlocking joints, combined with the use of tenons, was that they eliminated the need to nail or even peg flat tiles, which in those days didn't always have a tenon but a simple hole.

And last but not least, a rhombus in the center of the tile facilitated manufacture (drying and firing), stiffened the tile, efficiently channeled run-off by separating...