Replies

1. 
   mikeljon | Jun 21, 2020 08:44am | #1

   see this thread; thanks for bringing up the memories: https://www.finehomebuilding.com/forum/insulating-an-acrylic-bathtub

2. 
   MM1973 | Jun 21, 2020 11:57pm | #2

   Thanks, this covers foam, any opinions about mortar?

3. 
   jlyda | Jun 22, 2020 03:09am | #3

   It depends on the tub. Some manufacturers insist on concrete base, so check with your manufacturer as if you differ from their install, warranty may be void. Also, some acrylic tubs are built a lot more robust than others. I would never use foam on some of the cheaper/thinner brands (in truth would never install those tubs anyways). If there is no issue w/ the manufacturer and tub is strong I prefer foam. Mainly b/c it’s easier and does not add extra weight to the floor. Foam can raise the tub as it expands, best to weigh it down on the base and place a couple temp boards around the top screwed to the framing to keep it in place.

4. 
   Frankie | Jun 22, 2020 03:15pm | #4

   Set tub in a pile of USG's Structolite. Lightweight (when dry) and will support tub well. Stiff mix is best.

   Frankie

5. 
   sawdust_steve | Jun 23, 2020 07:54am | #5

   I like Structolite too for all the reasons Frankie mentioned.