New bathtub creaks when standing in it

This is a tub with styrofoam base. It only does it when you step on the back end. I noticed the stringer I put for the back doesnt make contact with the tub but Im not sure if I was supposed to put a stringer for the back anyway. Its a steel tub. With tubs with styrofoam are you not supposed to use any mortar to place them in?

The floor must be flat and level. IF it isn't, and there are any gaps, the thing will rock and make noise. MOst are not designed to hang from the ledger board. NOt sure what access you may still have, but it will be an annoyance forever if you don't address it. The movement will also stress the caulk joint between the tub and the wall.

Nothing has been mounted permanently except the stringers. Im thinking the stringers might be the problem. The floor is concrete slab. I noticed when I pulled the tub off the stringers and stood in it it didnt creak. I think the left end of the stringer is ever so slightly lower than the right. Also I was going to ask, is the tub supposed to be on the stringer, make contact with it, or be right above it not making direct contact?

If the tub sits flat and level in place without the stringers, doesn't make any noise, then you should still install stringers, but they could go right up to the bottom of the tub edge...the tub should NOT hang from the stringers. They are there to keep the edge from deflecting and keep the tub from tipping. If the tub doesn't sit flat and level, then you need to put something underneath to make it do so.

jadnashua said:

If the tub sits flat and level in place without the stringers, doesn't make any noise, then you should still install stringers, but they could go right up to the bottom of the tub edge...the tub should NOT hang from the stringers. They are there to keep the edge from deflecting and keep the tub from tipping. If the tub doesn't sit flat and level, then you need to put something underneath to make it do so.

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Ok, then I think I need to remove the main stringer and lower it so its just off the tub. What about placing the tub in a mortar bed? Do you do that with tubs that have a styrofoam base?

You can, and it may be necessary if it does not sit flat and level on your floor. Do not try to make a flat bed of the mortar...Terry likes to place a bunch of piles of the stuff spaced around, then push the tub into it until it is level. If you set the stringers perfectly level (assuming the edge is, too - it may not be!), then you can stop when it hits the stringers. Then, leave it alone until the mortar sets. Depending on your access, you may need to make the drain connection at the same time you set it. It takes some careful measurements to get it all configured, as if you need to set and make the drain connection at the same time, you only get one chance.