[mistyinca]

We have an oval drop in bathtub (don't know the brand). It was pulled from the existing tiled frame, and we laid new tile and are trying to reset the tub. We used mortar, and after a few days, the tub was rocking... seemed like it was unsupported in the front right quadrant.

I've seen varying opinions on what medium to use under the tub to set it with. Could you please provide some step by step instrutions on how to properly set it, including product suggestions?

Thank you,

[Milo Dolezal]

Hello Mystinca,

I assume you have built a box for your drop-in tub to be set into. That box should be about 2" higher than the height of the tub, leaving space between bottom of the tub and the floor.

Take a sheet of 5/8" or 3/4" plywood, put it on top of the box and mark outline of the tub - less one inch. Cut it out. Screw ply into the frame of the box. Dry-Test-Set the tub: place it into the box making sure it fits, edges overlap the cut-out opening in the ply, and tub sits about 2" above the floor.

Mix large bag of mortar, or concrete mix. Place sheet of asphalt paper on the floor inside the box. Shovel in mixed mortar, on top of the asphalt paper. Place concrete the way, so it is an elongated blob under the floor of the but, in the middle, where tub will be sitting. Be generous: mold it so the mortar mix is much higher than the 2" of space you have.

Now, take the tub and put it into the opening, on top of the wet mixture. Shake with the tub back 'n' forth until it slowly pushes excess of mortar to the side and edges of the tub now touch the plywood all around. If the tub doesn't want to go down easily, place a towel inside the tub, step inside and move your body to shake with the tub. Once the edges sit on top of the plywood, step out. Quickly center tub on the box. You have around 5 minutes to maneuver the tub.

Let the mix completely dry. Do not attempt to move or reposition the tub or you will break the grip of the concrete on the tub and tub will be loose. Usually, we leave it to dry over night. Next day, proceed with finishing the tub box as you wish.

As mentioned above, we use Mortar Mix or pre-mixed Concrete under the tub. From my experience, I would not recommend Joint compound, Stucco mix, or insulation Foam from a spray can for this application.

Hope that helps

Milo