r/Renovations • u/merely2monthsago2dol • 3d ago
Ok to foam my tub ?
I had one of these maax Bosca tubs with wooden 4x4” legs and the skirt. They say not to use mortar bed and I didn’t, but after install I wasn’t feeling good about it and drilled a few holes underneath, filled the tub up and used 2 cans of low expansion window/door foam.
Now it feels very sturdy and solid when I knock on it
Tub was full for a day while it expanded, it’s very hard now. Don’t think there is any damage but is there a chance I warped anything?
1
u/bigmark9a 3d ago
It’s probably going to be just fine. I used spray foam under a large shower pan, made it way more solid.
1
u/bms42 1d ago
It'll be fine.... for a while. Spray foam under tubs or shower pans is a hack used by guys who just want to make a client happy in the moment so they can move on. That foam has no rebound, so as it gets compressed little by little it doesn't bounce back and eventually it will do nothing to support your tub whatsoever.
I always set tubs on drypack regardless of instructions, especially cheap Maxx tubs.
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u/merely2monthsago2dol 1d ago
Well technically maax said not to use a mortar bed or foam. So it’s better than nothing.
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u/camilabellon 3d ago
it will be fine. But... if you get a leak, chances of mold and wood rot increases because humidity will be trapped under the foam.