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Uncoupling mat tile underlayment vs concrete board
Posted on 10/29/23 at 5:16 pm
Posted on 10/29/23 at 5:16 pm
Anyone used schluter ditra polyethylene underlayment for tile laying over plywood instead of installing concrete board? I’ve got a small tile job to do at the house and started my YouTube research since it’s been a while for me. I see people using this membrane that you thin set to the plywood, then lay the tile on top. Any opinions from users?
3
Posted on 10/29/23 at 11:24 pm to Gee Grenouille
I have had two bathrooms totally redone in the last 3 years. One bathroom with the cement board and one with Schluter DITRA heat. Love the heated floor, but the grout is cracking/crumbling in the DITRA heat bathroom. Contractor thinks the floor is flexing and I need to add some piers and extra support under it. I’m sure there is some truth to that, but since it is the only floor that is doing it; I’m not totally convinced. Possible the tile guy who didn’t speak English didn’t quite do it all correctly, so it may not be Schluter’s fault. I don’t know.
I think wire mesh and mortar bed is the way to go. My 70 year old tile floors were still in good shape and a pain to remove. The old ways are sometimes better than the new.
I think wire mesh and mortar bed is the way to go. My 70 year old tile floors were still in good shape and a pain to remove. The old ways are sometimes better than the new.
Posted on 10/30/23 at 1:54 am to Gee Grenouille
Ditra is absolutely the way to go, unless you can find an old school tile guy that knows how and is willing to set the tiles in a mortar bed.
With cement board, they are heavier, more difficult to cut to fit, seams must be taped, joints must be staggered, and they also need to be set in mortar. It becomes one with the subfloor, whereas ditra is an uncoupling membrane, the fleece on the back allows the ditra and plywood to move independently.
With cement board, they are heavier, more difficult to cut to fit, seams must be taped, joints must be staggered, and they also need to be set in mortar. It becomes one with the subfloor, whereas ditra is an uncoupling membrane, the fleece on the back allows the ditra and plywood to move independently.
Posted on 10/30/23 at 2:00 am to ChEgrad
Your floor may not be suitable for tile or stone as is. The first thing to check is the size of your joists, the unsupported span of the joists, and the spacing in between the joists. Take those numbers and run them through a span table for tile. Also, what is the subfloor? Plywood? Planks? If plywood what is the thickness? Lots of things to take into account, but the contractor is probably correct. Shame he didn’t let you know before the tile was installed. Sorry for your troubles.
Posted on 10/30/23 at 7:33 am to 9rocket
All good points. I'm replacing the subfloor with 3/4" plywood that's going on top of 2*14 joists. Once I remove the subfloor I'll know the condition of the joists but I suspect I won't have many issues. I have a scabbing plan if I do find any soft spots, and I already have some bricks for support if I need to add some stability underneath the joists. Nephews are doing the demo and providing lifting support for the 3/4" plywood. It's a 180sf area and I'm hoping to knock it out in two days. I'd love to be laying tile on the second morning.
Posted on 10/30/23 at 8:46 am to Gee Grenouille
Many times adding a beam supported on both ends midway of your span is enough to do the trick. 3/4 ply is good. If your flooring will be natural stone two layers of plywood will be required.
Posted on 10/30/23 at 10:38 am to Gee Grenouille
I'm no tile expert but I've remodeled 3 bathrooms, a kitchen, and a couple rooms of tile.
The purpose of the cement board is to add the rigidity under the tile on wood so that nothing moves. IMO its overdone mortaring in but that shite doesn't move when you do it. My upstairs creaks everywhere but my upstairs bathroom that is tile over cement board.
One thing to consider is what is there now compared to putting cement board down for example will be taller (thicker? so you are probably going to want a good threshold.
The purpose of the cement board is to add the rigidity under the tile on wood so that nothing moves. IMO its overdone mortaring in but that shite doesn't move when you do it. My upstairs creaks everywhere but my upstairs bathroom that is tile over cement board.
One thing to consider is what is there now compared to putting cement board down for example will be taller (thicker? so you are probably going to want a good threshold.
Posted on 10/30/23 at 11:41 am to 9rocket
quote:
Your floor may not be suitable for tile or stone as is. The first thing to check is the size of your joists, the unsupported span of the joists, and the spacing in between the joists.
Well, there was a tile floor there before installed in 1978. Small tiles over a mortar bed. 3/4” ply subfloor. 16” on center floor joists. No issues. Now we have 12” marble tile on DITRA heat and are having issues.
Posted on 10/30/23 at 1:29 pm to ChEgrad
quote:
Well, there was a tile floor there before installed in 1978. Small tiles over a mortar bed. 3/4” ply subfloor. 16” on center floor joists. No issues. Now we have 12” marble tile on DITRA heat and are having issues.
Again, I'm not a tile guy. But I thought if you weren't doing cement board they used to go with more plywood? I don't see how Ditra even with a mortar bed could come anywhere close to providing the base that plywood+cement board would offer? What am I missing?
In other words, if you are going with Ditra heat I don't see how you don't go with maybe a thinner ply+cement+ditra?
Posted on 10/30/23 at 2:32 pm to baldona
Cement board adds no structural benefit. It is merely an underpayment. The purpose of the mortar underneath is merely to eliminate any voids. Also, it is specified by the manufacturer. 1/4” for floors, unless you have to have additional height, in which case you would be better off adding another layer of plywood instead.
I much prefer ditra. Superior product, easier to work with, plus you get an uncoupling membrane.
I much prefer ditra. Superior product, easier to work with, plus you get an uncoupling membrane.
Posted on 10/30/23 at 2:34 pm to ChEgrad
Marble is a natural stone, which requires a floor that is twice as stout as ceramic or porcelain. Also requires two layers of plywood.
For more on this and to answer any questions you may have -
Check out the John Bridge Forums, ceramic tile advice forums.
For more on this and to answer any questions you may have -
Check out the John Bridge Forums, ceramic tile advice forums.
This post was edited on 10/30/23 at 2:55 pm
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