Installing a Fiberglass shower

[Richmast]

I have a one piece large shower stall which has a seat. The fiberglass base sits on its own platform. I have been told that I should set the base in concret to give the base a stronger fondation. It seems to me that the fiberglass is moulded to the platform and the the additional concret placed between the platform and the floor would not make that much difference. So what would be the best solution? Thanks

[construct30]

You don't need a full mud bed, but there should be "feet" or legs that will need to be shimmed. You can glue, with glue that won't hurt plastics, cedar or treated wood shims or mix some mortar. I like to shim around the drain also. If you do nothing, the floor will crack around the edge, and the drain may start leaking.

[jadnashua]

Fiberglass will flex if not supported. Over time, that will cause microfractures and eventually it will crack all the way through. Unless the bottom is solid and the floor is flat, it is best to support the bottom in something. The chances of having a perfectly flat floor is slim to none. Embedding it in something solid also gives you the chance to make the thing perfectly flat, which means it will drain properly.