The shower pan in our MB is bowed and water runs away from the drain. The cost to R&R the shower and pan is too expensive. The base is very stable. Can I put tile directly on the cultured marble base after I scuff it up suffciently. Do I need to use a special adhesive?
Forget using ceramic or stone tile on that base--it is too unstable. How would you create a sloping surface?
Actually, it is not a shower pan that is bowed, but rather a shower receptor. Your receptor probably bowed because of inferior design or workmanship. Putting tile on top of it is a waste of money. The receptor, and the lower course of tiles bordering the top of the receptor need to be replaced. Before the new tiles can be installed, a waterproofing membrane must bridge between the membrane behind the existing tiles, and the lip of the new receptor. If this is not possible, the waterproofing must flash behind the old setting bed.
Don't waste your time trying to get by with a patch when you need to replace the shower pan. Going over the existing cultured marble will only be a temporary inadequate fix. Do it right, install a new pan with prefloat and a membrane according to the UPC ( Uniform Plumbing Code ), you won't regret it like you will tiling over the cultured marble.