Matching the old school mortar bed.

GA native

Senior Member
The master bath in my house had a garden tub. The wife has come to my side, regarding these tubs as useless. So we have purchased a new tub, new faucet, and a plumber is coming out to rough it in tomorrow.

The interesting thing is, this bathroom floor has a 1 1/2" mortar bed. Common thing for houses built before the 70's, but unusual for a house built in 84'. The garden tub was installed first, and the mortar bed poured up to it. Leaving a 6'x4' void to be filled.

Now generally, in a bathroom remodel, I chip out the whole mortar bed, build the subfloor up, add durock, and lay my tiles on top of that. But this floor is in good shape, and the wife likes the tiles. Plus I need to match the height of the existing floor. So I am planning to fill in the void, and lay tile on top of that.

So the question is: What do I use to make that bed? I lean towards sand mix concrete. Or type S mortar. Floor leveler is not the right tool for the job, and it would be prohibitively expensive, at $37 for 40lbs. And at $16 per 50lbs, bedding mortar is getting too pricey for 24 sq ft at 1 1/2" (4.5 cubic feet).

I figure on 10- 60 lb bags (for sand mix or type s), so cost is a factor. $50 for sand mix or type s. $200 for bedding mortar. And forget about the leveler...
 

GA native

Senior Member
Pictures of the task at hand.
 

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rjcruiser

Senior Member
I'd just use cheap concrete or mortar that comes in the 60-80 lb bags. Just make sure you get it level, or you'll have trouble setting those tiles.

Or...if you get the self leveling stuff to get it level and then pop a 1/2" piece of plywood on top to get it up to the level you need, that would work too. then you're not using so much leveler.
 

Crakajak

Daily Driveler News Team
Shouldn't there be a moisture barrier between the bedding material and the plywood?
 

GA native

Senior Member
Shouldn't there be a moisture barrier between the bedding material and the plywood?

The technical term is a bonded slab and a floating slab.

Because the water is contained in the tub, a vapor barrier isn't necessary. A little bit of water dripping off a body isn't going to harm anything. The mortar bed in a shower needs a moisture barrier.
 

GA native

Senior Member
I'd just use cheap concrete or mortar that comes in the 60-80 lb bags. Just make sure you get it level, or you'll have trouble setting those tiles.

Or...if you get the self leveling stuff to get it level and then pop a 1/2" piece of plywood on top to get it up to the level you need, that would work too. then you're not using so much leveler.

Once the plumber finishes butchering my subfloor, I plan to skin over the subfloor with 1/4" CDX. Glue it and tattoo it, then start pouring mud. Leaving a 1 1/4" mud bed to fill.

Now if I scab the subfloor with 3/4", that leaves a 3/4" mortar bed. 5 bags of type s would simplify things tremendously. Hmm...

I think sand mix or type s would be fine, I'm just hoping to hear from someone who has been there and done that. Hate to ruin the whole project trying to save a few hundred bucks.
 

rjcruiser

Senior Member
Now if I scab the subfloor with 3/4", that leaves a 3/4" mortar bed. 5 bags of type s would simplify things tremendously. Hmm...

this is what I was thinking.

I would think the less leveler, the more solid it will be. Not any different than putting tile on any other subfloor.
 

naildrvr

Senior Member
I would go with dry pack or 3/4 plywood and 1/2" durock. That gives you 1-1/4" then tile on top of that.
 

chadf

Senior Member
I just raise the floor where needed by “floating” not tote 60lb bags of cement

Leave existing title if solid, build up the remodel hole solid with wood, seal good and do what’s needed to get finished look.

Measure 3x and trust your level !
 

WayneB

Senior Member
5:1 sand to portland cement for the dry pack.
just add enough water to 'wet' the grains of sand, not saturate. Spread and tamp level with trowel.
let sit 1-2 days, before you add tile.
Still done in commercial kitchens this way.
 
Or....there is a bag of mud at Lowes called "BED MUD." I have used it, and it lasts. It is ready to go. All u have to do is add water.
 
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