posted 11 years ago
I've never seen that. If your roof were super strong, the tub could be used in the upright position. It would store a lot of water. An overflow could keep it full, half full or at some other level. Toilet and wash water could gravity feed to point of use. In summer, a cooling roof pond could be maintained.
Used upside-down, most tubs would need a lot of clean up. Pipes and jets, wires, wood and foam cover the bottoms of tubs. All of the goo makes tub bottoms unsightly and difficult to bring to any sort of roof like smoothness.