I have a Kohler K-1219-L drop in alcove tub. The recommend (but not require) a mortar bed. With my tank butt I am putting it into a mortar bed, no debate about it.

My question is if there's an ideal thickness for the mortar bed. From reading Kohler's install instructions they just recommend setting the tub into one, no indication of thickness. So my first thought is to dump the mortar in there and thin it as it gets to the drain and just let it have a feather edge at the drain. My follow-up to that is that the mortar will be too thin, crack/shift/move, and cause me issues 5-10 years down the road. That's where raising the tub up 1" to give me at least a 1" thick mortar bed came to mind.

Am I just over thinking it? or should I ideally have a minimum thickness to the bed?



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If the tub is raised 1" that's too much. I use about 1" of wet mortar and wiggle and press the tub down into it. It's there more or less just to prevent the tub floor from flexing and cracking.

There is 1" clearance between the floor and bottom of tub at the drain, so it's more at the back end. Measure the height of the legs when you get the tub, so you will have enough under the back end of the tub. Here the spec sheet - [www.us.kohler.com]

OK. I'd prefer to not raise the tub anyways since it's a 20" tall soaking tub. Don't want it to feel like you need a step stool to get into the thing.

And I see what you are talking about now on the rough-in. I read it wrong and thought 1" was at about the midway point. This is why a second pair of eyes is a good thing.



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it is not even necessary to have 100% coverage with the cement. a few stratically placed pyramids of fairly dry mortar set too high will do it. don't skimp but don't overdo it. smush the tub down until you get the desired height and it is perfectly level etc....

Make sure the tub is absolutely level, before permanently setting it with mortar. Make sure you smoosh (technical term )the mortar,just enough to bring it back to level. Another poster recently didn't do that and was left with a problem.

Yeah, never done a mortar bed before. All the other tubs have been those cheap stamped porcelain 14" jobs in my father's rentals. So, plan to make sure the deck and everything is perfect before I even touch the mud.