# What type of morter to use under bathtub?



## angus242 (May 1, 2008)

You could use spray foam. Actually, there are new tubs that come with foam blocks attached to the bottom for support. Just make sure the tub has water in it before you spray and that the foam isn't going to go places you don't want it to!


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## CowboyAndy (Feb 19, 2008)

I thought about sprayfoam, but I am worried about it losing its rigidness over time...


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## angus242 (May 1, 2008)

Polyurethane foam will support it. It's more of a question of whether or not you can actually get a low-expanding foam in all the places it needs to be.
I would be careful. You don't want to use a thinset. Cement would be the best option. I believe thinset can actually shrink some so you may end up with a small gap under the tub 
I'd say foam or cement.
Don't worry about long term, roaches and polyurethane will be around longer than we will! :laughing:


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## Brik (Jan 16, 2007)

I have used "sand mix" mortar. Mixed to between peanut butter and pancake mix consistency. I built little cardboard dams to contain it and keep in from going where I didn't want it.


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