styrofoam sm under whirlpool soaker bathtub???

[gary]

I'm replacing my tub with a 5' whirlpool soaker tub. I would like to cut down on noise going into the basement when the pump is running. I have about 3" of space under the tub which would normally be just filled with mortar. Can I place a piece of 2" styrofoam sm under the tub and then top off with the mortar? I would probably build a small frame to keep the mortar in one piece. This tub is also supported by a ledger on 3 sides and has a built in/molded on skirt which also supports the tub on the 4th side.

If I am not mistaken I believe that they use this product under concrete so I imagine it can handle the pressure but am not sure if the bathtub application would work the same way. I would appreciate any insite. I should have delved into this sooner but I gotta get the tub in on Sunday as the family will start smelling. New tub came friday and old tub came out today (saturday).

Thx Gary

[m Ransley]

Foam transmits sound, you need isolation or absorption, call the manufacturer, fiberglass batts for sound may help but then you have condensation-mold concerns. Air circulation is important.

[Joe Bobst]

Wrongo! Polyurethane foams are some of the most acoustically dead materials there are. So, logically, some well placed panels of the stuff will be just what is needed to calm the uproar. Apply with common sense and clever strategy for best results. Good luck

Joe

[gary]

Thx. I didn't think SM transmitted soundl. Picked up 2" of SM today. tub not in yet still reframing up the bathroom. It was previously a 5'4" wide bathroom with a 5' tub. They did some creative ceramic work with a ledge to make up the difference. I am framing out one of the walls to fit the 5' tub...... I think I'm going to put the 2" os sm under the tub and then will have about 1.25" of mortar to go over that to set the tub. There is lots of room between the tub piping and the back wall which is an exterior wall for me. I am going to put 2" sm over this area under the tub lip too. Maybe the water in the tub won't cool down so fast in the winter time. I will also insulate in the joist space under the tub when I get to finishing the basement.