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Using spray foam on steel bathtub

We are renovating our bathroom and are about to install a new porcelain on steel bathtub. We were thinking about spraying around the sides of the tub with expanding foam insulation for support and heat retention. My concern is how much the foam expands and could that distort and crack the tub. It seems there would be plenty of ways for the foam to expand in other directions. ALSO we were thinking about doing this before we install the tub so we can trim off excess and minimize pressure problems. Any thoughts or experience with this?

Re: Using spray foam on steel bathtub

your better off not risking it. put down some rigid foam in side the tub shell. you can use a small can of spray foam to adhere the rigid though

Re: Using spray foam on steel bathtub

If you apply foam BEFORE you install the tub, I doubt that you could fit the tub in place.

If the tub is sitting next to an exterior wall, just insulate the wall to code. Don't forget to install an access door for future plumbing repairs.

Re: Using spray foam on steel bathtub

Thanks for the input. I did put a layer of foam on the tub to help damper the sound and we will stuff it with fiberglass insulation after we install it (Access through open walls). I don't think there will be a fit problem as the foam is not protruding beyond the lip of the tub... if there is, I guess I'll have to sc**** it off. Thank you again.

Re: Using spray foam on steel bathtub

Should be fine steel is pretty durable I have done this with fiberglass tubs I did use window and door though to not over expand I am a plumber and if you were worried like I said use window and door it doesn't over expand but sounds like you got it!

Re: Using spray foam on steel bathtub

expanding foam should not distort a steel tub, but to be sure take (3) 5 gal buckets, fill them with water to the top. put them next to each other in the tub, then inject foam under tub. the weight of the water buckets will prevent any distortion of tub. I do this in fiberglass tubs allot, works fine.

best of luck, Patrick from Resurface Spe******t of cape cod. tub refinishing experts

Re: Using spray foam on steel bathtub

The easiest way to accomplish this is to visit http://www.insulatedbathtub.com great product and makes it very simple to insulate your tub before install.

Re: Using spray foam on steel bathtub


You are not going hurt that tub. I am sure that you noticed the weight when it was carried into the house. One that I did on a couple tubs like that, is to use mastic to cover the outside of the tub. I am assuming that you are going to cover that area to not be seen. You did not mention that this is a claw foot tub.

Then, once the tub is in place, spray all the foam that you like. Just do not spray too much in one area. Spray, let it expand, spray more if needed. There is not hard set rule on this stuff. Look and see what it is doing.

If your tub is going into a newer house, I suggest that you reinforce the structure under that bathroom. New houses are not designed to carry that kind of weight. I also drill a couple 3/4" or 1" holes in the floor, just in case there is a water leak, I want it to run into the basement instead of pooling under the tub. Provided the tub is on the first floor, and you have a basement or crawl space. Put stainless steel screen over the holes so that tiny critters don't come in.


Handy Andy In Mt Airy NC

Re: Using spray foam on steel bathtub

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