Just had a new steel tub installed. The floor was not level so the tub was shimmed to be level. There is a piece of plywood under the foam beneath the American Standard Cadet tub.

The tub creaks a LOT. I am sure it is because it was not bedded, but as it is now installed, how can I fix it? I have access at the tap end only. Some of the styrofoam was removed by the installer (my BIL) who said he was told that it was not structural and wouldn't matter.

The tub was installed with a 2x4 stringer along the long side. All is tiled, grouted and sealed now.

I tried a bit of foam, but didn't do complete job as I wasn't sure it was the best method.

It does not creak as much when full of water, which confirms to me, as well as visual and tactile inspection does, that the tub is rubbing on the styrofoam base.

Help?

Your plumber's a BIL? What's a BIL an d what qualifies him to do plumbing? There's no doubt that you got a faulty installation.
I tried a bit of foam, but didn't do complete job as I wasn't sure it was the best method. Foam is not the best bedding material. It's full of air that will compress. Try this. Go in from the tub access panel and shove cement or motor in under where you would be seated. Let the bedding cure and set up. Now try it. Good luck, Tom

BIL = brother in law (standard internet shorthand, sorry). He is a builder. Tub instructions did not mention mortar.
Tub access is only at tap end, and I can't very well shove anything under length of tub.. is there another way of putting it there? What kind of cement?
The floor beneath the tub is 1954 plank floor, which complicates things a little as well, as it has gaps.

Incidentally, the plumber he consulted with that works for them said no need to mortar, had never heard of or done mortar installs. And advised chipping out all the foam.

incidentally, the plumber he consulted with that works for them said no need to mortar, had never heard of or done mortar installs Bedding steel and plastic tubs with cement or mortar is a standard practice. I'm surprised your plumber doesn't know this. Is done to "sturdy" up the bottom so it doesn't flex and make noise. Any cement will do. Foam is useless as it consists of air bubbles tat will compress in time. Remove the foam and replace with cement or mortar, Good luck, Tom

By "remove the foam" the plumber meant to take out the white styrofoam that came attached to the bottom of the tub.

Can you be more specific about the cement or mortar? What type? Do I need to fill the open pockets of the styrofoam block under the tub? How much mortar or cement? How can I get it to the back of the tub, since I can only access via tap end, via a small access door?

by "remove the foam" the plumber meant to take out the white styrofoam that came attached to the bottom of the tub. Are you sure that you hired a licensed plumber and not a handiman? The foam was placed there by the manufacture for bedding to prevent exactly what you're complaining./ As we talk more I'm beginning to have real concerns about your plumbers plumbing knowledge. Regards, Tom

No, I didn't hire a licenced plumber. See above, re brother-in-law, a general builder, who spoke to his licenced plumber, who said rip out the styrofoam, and who doesn't ever bed into mortar.

Point is, tub is IN, tile is IN, and now I have to resolve this problem. I have a plank subfloor, limited access and a need for more information as to how exactly, to put mortar underneath the installed tub in a way that won't just pave the floor and drip into the basement.