Acrylic bathtub support

Pete Sahr

I installed a new one-piece acrylic / fiberglass bathtub/surround. It is complete, sheetrocked in and painted. When I shift my weight in the shower, I can hear a slight crinkling sound coming from the bottom of the tub and I'm afraid it's going to crack. Is there anything i can spray underneath (I can access under the tub from from the basement) to give support to the tub? Someone suggested expanding spray foam, but I'm not sure about that. Has anyone else tried that? Any suggestions would be greatly appreciated.

Pete

vsheetz

It should have been installed in a bed of morter to give it support and a solid feeling. I dunno about spray foam - maybe somebody has experience with retrofit suggestions.

wrangler

Do you recall what the bottom looked like? Honeycomb/egg crate? If so, it would be hard to fill all the voids from below. If not, spray foam wouild work, but I would fill the tub first to prevent the foam from warping the tub. Like previously stated, it would have been best to have set it into a morter or mud bed.

__________________
Man of many hats

Thurman

I have successfully used spray foam to do this very thing on three (3) tub/shower units, one in my own home. Access to the bottom of the tub is the key here. IF AT ALL possible somehow place a contractors grade, large garbage bad in between the flooring and the bottom of the tub, then fill the bag with the foam. I have found that this tends to keep the foam in the area you are needing it, rather than having it just seep where it want to go. As stated, and important, I do fill the tubs about half-way with water (full should be fine also) to prevent the foam from causing the bottom of the tub to rise--ANY. The added weight of the water will make the foam spread out rather than try to rise also. Another trick I have learned it to buy some tubing which just fits over the tube of the spray foam tube, tape it to a dowel rod, yardstick, something solid, so you can guide the foam where you want it to go. This works when accessing the tub from one side. You may be able to use the tubing from under the tub, the basement side, to help place the foam. Think it through before actually spraying. Good Luck, David

Bud Cline

All good information above but I can't stress enough that you use a minimal-expanding foam and not the 3X's (or more) foam. There is also non-expanding foam available.

I have seen the industrial strength foam raise heavy tubs several times. It can also ruin door and window jambs by pushing them out of place.

Fill the tub to the overflow and leave the water in the tub overnight to be safe. If too much expanding foam is used and it still needs a place to go it will move mountains in some cases.

Jtroxell

I am going to have to do this to the tub in our house. Can you recommend some brands of foam and tell me anything else I need to know to make sure I'm getting the right stuff? Most of the spray foam I've seen is just gap and crack filler. That would not work, correct?

Thanks,
Joel