Bathtub mortar bed

[brandonmg47]

I'm going to install an acrylic jacuzzi tub with the ~6 foam feet. I'd like to use the mapei 4 to 1 mud bed mix. I was thinking about use 2 bags to make sure I have full support back to front of the tub including around the drain. Right now, dry fitting it with no mortar bed, I have a great fit with the ledger board and have marked all studs around the tub as well as predrilled and screwed it in to test the furring out I had to do. I'm now fully prepared to remove it then use the mud bed mix to ensure great support. My question is this: Has anyone ever had any issues not being able to set the tub in place as it was when dry fitting it because the mortar bed has raised the whole tub? I'm concerned I won't be able to squeeze enough of the mortar out from under the foam feet when stepping in the tub before it cures. Thanks!

 

[CENTRALFL]

I would first suggest following manufacturer instructions.

Is it possible to roughly calculate the volume needed? You have a rough idea of tub surface area. And you know the height from the floor from the foam squares. If you are going to use the foam squares, minus that volume.

Make sure to not enclose your drain piping, like in this thread : https://terrylove.com/forums/index.php?threads/stuck-drain-assembly-by-mortar.112264/

 

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[Reach4]

My question is this: Has anyone ever had any issues not being able to set the tub in place as it was when dry fitting it because the mortar bed has raised the whole tub? I'm concerned I won't be able to squeeze enough of the mortar out from under the foam feet when stepping in the tub before it cures.

Do not use a mortar bed, at least the way I would picture a bed. Search this forum for

using the search box above.
https://terrylove.com/forums/index.php?threads/fist-tub-install-please-help.84586/ is a useful thread.

 

[Taylorjm]

When I create a mortar bed I measure the area under the tub I want supported and transfer that to the floor. Then add mortar. I use a piece of wire with tape on it measured at the right depth and stick it into the mortar bed. Then set the tub.

 

[brandonmg47]

I think I have a strategy thanks to your guys's help: Use enough mortar to fill the calculated volume underneath the tub (minus the foam feet). Then use multiple piles under the tub and around the foam feet to make sure not too much stays under the foam feet raising the whole tub. Also, stay clear of the drain, so future drain maintenance is easy. I'm also going to use synthetic roofing underlayment (as opposed to plastic) that is essentially waterproof, but also breathes, so no mold will come around. It's also stronger. Does this sound like a solid plan?