Installed an Americast tub a couple months ago- used 2x4 ledgers along back, as directed. Mfr does not recommend mud under the tub (will void warranty if it is used)- I was skeptical, but followed their recommendation.
Tile is in and finished/caulked, and the tub has started creaking- along the bottom of the tub. Dang!
Any ideas why they don't want mud under the tub? I have some access (via crawlspace) under the tub- it's sitting on 3/4 ply b/w a couple of I-joists- there's access through a slot where the waste/overflow drains out. Any suggestions on how to get this thing to quiet down?
Edit: In reviewing some past threads on this issue, sounds like spray foam is a no-go...possibility of delaminating the tub structure. Some seem to bed this tub in mortar (regardless of mfr. recommendation), using visqueen b/w tub and mud- presumably to keep mud away from tub surfaces, where delaminating might occur. As mentioned, I've got little access via the waste/overflow slot in the floor- I might be able to shove some mortar in via that access, but could only push it in so far. Trying to protect the surface of the tub with visqueen could be tough/impossible. Is there any real risk in delam due to mortar contact?
Creaking = movement....if I do nothing, am I risking eventual cracks/failure of the tub?
I'd rather not call Americast about this...not optimistic I'd get any useful info....