The best foam for under a bath tub.

[Terry]

Always a good question.
For those of you plumbers that are using expanding foam under tubs, what is the best?
American Standard Americast tubs sometimes need something underneath to prevent the creaking and the squeaking. Some people use mortar too. I don't know if A/S is into mortar though.
My personal preference is mortar, but if you don't have access for that, then sometimes using a foam can with tubing can be useful.

[dlarrivee]

I have a 2 piece from MAAX and they recommend a bed of mortar with a 2mil sheet of poly over it...

I'm interested to hear what everyone has to say...