mollie,

If your tub didn't come with a manual, you can go on most any manufacturer's website to see how they want their tub installed.

Some want them set in a bed of mortar, some choose their tubs to be glued to the subfloor with construction adhesive.

Some people recommend foam, but foam flexes and it's something I'd never use.

I almost always set tubs in a bed of mortar. It does two things: It gives absolute support, and it allows me to level the tub if the floor is slightly out of level.

For a drop-in, you want to set the tub so the rim of the tub just touches the deck of the tub. You don't want the tub hanging by the rim, or it can lead to the tub eventually cracking, as their isn't enough reinforcment in the tub to support it by the rim.

Ususlly no additional framing is needed to support the weight of a tub.

If you wanted to elevate the tub, you could build a platform for it to sit on. Then the weight of the tub would be transferred to the fdootprint of the larger platform, reducing the "pounds per square foot" lod placed on your floor framing.

As far as insulation, you can use canned foam, commercial spray foam, or wrap it in fiberglass. Or if it's a circulating tub, you can add an aftermarket in-line water heater for about $250.

If you use canned or spray foam to insulate the tub, if it's a jetted or circulating tub, be careful where the foam goes. You don't want it to screw up your tub's plumbing.

Mongo

Just installed mine today..as Mongo pointed out, it was set in a bed of mortar-like product..It is elevated, so it sits on a "deck" which is topped by CUB and then granite..I didn't insulate it any further then the walls nearby which ahve insulation..Funny, the jetted tub i removed had no additional inuslation either..

I had no idea you could sit an acrylic tub in a bed of mortar. It is a soaker tub, no jets. I am trying to decide between the Maxx Living 36x72 or Maxx Palace (approx same size). Any suggestions? I am older and need arm rests, grab bar so looking for something like that.

Mongo, you mentioned you installed one for your mother earlier, which tub did you choose? How did you set it?

For insulation we sprayed Icynene around the tub at the same time we did the walls. Besides insulating, it also deadens the sound & is a good environmental product: no formaldehyde, no petroleum ingredients, & no fiberglass. (great in the attic too)