View Full Version : How to put the mortar bed under a bathtub

07-13-2008, 10:09 AM
Hello! I suspect this has been answered on here somewhere, and I have found mentions of Terry's preferred method of using mortar "columns". We're doing a major bathroom remodel and it's time to get the bathtub in there. I've got a Jetta soaking tub, which comes with very scant installation instructions. I called the company who recommended a layer of plastic on the sub-floor (which is wood), 1"+ of mortar, another layer of plastic, and the tub. They couldn't really speak to using stringers on the side walls (it's a 3-wall installation without an apron), and the instructions specifically say the lip should not be supported by framing members. The owner of the tub store also talked about the "column" method, and even drew me a schematic, using "1/2 a muffin tin" of mortar near the foot and "1/2 a yogurt cup" of mortar at the head. I've been literally having nightmares about this process for the last couple of weeks!

- Do we put plastic under and over the mortar?
- How many "columns"? The tub has a solid plywood base.
- If we use columns should there be a solid layer of mortar as a base?
- Assuming we can calculate the finish height of the tub, including the 1" of mortar, should we attach stringers to the walls? We can't actually push the tub in from the front. One side wall was a doorway, and we haven't yet framed it in, so the tub in coming in from the side and will be rotated and dropped in. At least that's the theory :-)

Thanks in advance for your help and advice!

Dunbar Plumbing
07-13-2008, 10:26 AM
I mix up two bags of mortar somewhat tight, I'll etch a imprint of where the tub actually sits on the floor before doing so, then I set height of the mortar about 3" so it squeezes out to the sides.

From there I pack those sides back in tight, make sure that I've brought that up as close to the tub drain as I can.

If it is a steel tub, put plastic on the top side. I've never had a problem with setting mortar on a wood floor but once it's dry, it's always stays dry from that point on. Plastic could work on the below as well, but not necessary.

07-13-2008, 10:34 AM

Thanks! That sounds pretty straightforward.