View Full Version : Tub installation on basement floor

05-16-2007, 07:30 PM
My basement had a rough in for a tub when the house was built. I have added the connection for the waste drain, but when I set the tub in place I notice that the cut out in the concrete causes 2 of the eight 'feet' on the bottom of the tub to hang free. I am placing the tub directly on the concrete floor. These 2 feet don't come into contact with anything. Do I add some concrete? Or will I be ok without it?

05-17-2007, 05:43 AM
The tub should be supported and should not rock. If the feet are structural and not just decorative, then they should all be in solid contact with the floor. If not, the tub may not drain properly, or it may rock and crack the connection to the drain, or break the caulk seals to the walls which could admit water around the side of the tub, or all of the above.

If it were me, I'd put a layer of SLC on the entire bathroom floor to achieve level.

05-17-2007, 06:38 AM
What is the tub made of? Cast iron tubs, for example, can be supported by the front apron and the ledger board under the rear edge.

05-17-2007, 11:31 AM
The tub is plastic with heavy gauge fiberglass? or plastic as a base. It has to be level; that is sure. And all eight of the support feet need to keep contact with the floor. I think I will fill in about half of the rough opening with concrete then level the entire floor with self leveling concrete. If anyone has other suggestions, I'm ready..... I can't get to this project until next week anyway.

Filling in the rough opening even half way still leaves plenty of room to work on the drain, if necessary. Is there any reason I shouldn't fill part of the rough in?

05-17-2007, 02:07 PM
Plastic/fiberglass tubs need support sufficient to keep their bottoms from *ever* flexing even a little. Since I have never seen such a tub with eight feet, I can only guess here ... so maybe yours has a relatively weak bottom that actually needs all those feet to be firm at all, or maybe yours has a very strong bottom that does not need the usual bed of concrete recommended as direct support for the bottom. Personally, I would either remove or shorten those feet and set the tub bottom down onto a bed of sand-mix concrete.

05-17-2007, 04:55 PM
if you want to find out more about setting an (acrylic coated) fiberglass shell tub like that, search on "mortar" and setting tub. A user here named randyj posted some pictures here on someone's thread a couple months ago, and he hasn't been back much since so scroll through his recent posts and you'll find the pictures easily.


05-23-2007, 10:39 AM
Post 6 in the "mortar under shower" thread shows the exact tub that I am installing. I filled in the rough cut out enough to allow all the feet to have contact with the floor, then I put down about 1/4" SLC to level the floor, which works great BTW, if a little pricey. I'll likely add the mortar base to solidify the bottom (what's another $5); I'm just not ready to make the install permanent ATM.

Thanks everyone for the help.

05-23-2007, 10:50 AM
use a sheet (big plastic bag) to separate the mortar from the tub so it won't stick. In case that is what you meant by saying not permanent at the moment.