Howdy,

In my ongoing saga of our remodel from Hell, I realized that they (my wife and the Depot Designer) used the wrong dimensions for the whirlpool tub.

I need to mount the tub on a platform so that it can be at the proper height.

The tub needs to sit 18 1/4" above the level of the subfloor. In order to use the access panels (cabinet doars) which are 18X24, I need to raise the
platform by 6". Should I use pressure treated lumber or Cedar (or something decay resistant) to build the platform?

I was going to use 1/2" plywood and 1/4" Hardibacker for the top of the platform.

Is using treated lumber overkill?

Same for the hardibacker?

Also, should I bolt the tub to the platform?

They (American Standard) suggest that the use of a foundation base
consisting of cement (e.g. Sakrete), mortar, or grout will help provide a solid and secure installation.

Anything else I should do?

As always, Thanks!!

speedball1

Hi Dan, Welcome back,

(1) "I need to raise the platform by 6". Should I use pressure treated lumber or Cedar (or something decay resistant) to build the platform?"
Since you're going to have moisture and high humidity so I would use a good grade of lumber
(2) "I was going to use 1/2" plywood and 1/4" Hardibacker for the top of the platform."
You'll have a lot of weight with a fulol tub and a person in there. I'd opt for overkill and go with 3/4" plywood plus the 1/4" Hardibacker
(3) "Is using treated lumber overkill? Same for the hardibacker?"
No I don't think so.
(4)'They (American Standard) suggest that the use of a foundation base
consisting of cement (e.g. Sakrete), mortar, or grout will help provide a solid and secure installation. Anything else I should do?"
Just make very sure the tub is bedded good.
Good luck, Tom