I'm helping my friend with fixing up his house & he wants to switch from a small shower stall to a shower/tub unit. He wants this American Standard Saver tub https://www.lowes.com/pd/American-S...-Acrylic-Rectangular-Right-Hand-Drain/3394192 with it's matching surround. The instructions say to use a mortar bed underneath (although I'm still waiting to hear from the mfr on how much of a gap there is between the floor & the tub's bottom to know how high it needs to be. I've seen all sorts of different suggestions and opinions on what to use for the mortar bed, what to put under it, what consistency to make it (some say barely wet, others say wetter, etc), and whether or not to put a plastic barrier between the tub & the mortar bed. I saw the spray foam suggestion but I've seen how spray foam does longterm & it is not a good idea, IMO. Someone suggested the Sika expanding foam that hardens like concrete, but my concern would be it could expand too much. I've seen some people suggest thinset material for mortar and others suggest "drywall mud". So, some questions: 1. What sort of mortar is the easiest to work with that would yield the best results? Would drywall mud work? 2. What is the best mixing method? 3. How high does the mortar bed need to be? (mfr recommended two 80lb bags of concrete) 4. Can we use roofing felt under the mortar bed? 5. Should we use some sort of plastic sheet or thin barrier/coating on top of the mortar bed to prevent it from clinging to the tub in case the tub needs to be pulled for a repair? 6. For the drain, if the mfr says not to use putty (to use silicone instead), do we still need caulk if we get a caulkless drain (similar to the EZ-Flow shower drain Frodo showed in another thread)? 7. What parts would we need to do a direct connect drain (with trap below the tub's drain instead of below the overflow)? I know we'd need some sort of 1-1/2" straight piece that is threaded on the inside. I saw one from Westbrass. I know we will need the overflow shoe (or what is that piece called?), gasket, plate, etc. We'll need the pipe to go down from the overflow and a sweep to carry it to a sanitary tee for the drain and then the P-trap. I think there needs to be a tub gasket between the drain and the bottom of the tub and we'll need the part that screws in to the threads from the top. Any help would be appreciated. Pictures are welcome since they help me visualize better.