Decoupling membrane under ceramic tiles?

[Traveler004]

I'm planning on putting down ceramic tiles on a concrete basement floor. I'm told a decoupling membrane is going to help prevent cracking due to movement because of temperature changes. Concrete floor being really cold in winter, the ceramic tile in front of the wood stove being quite warm. Anyone done this before? Does the decoupling membrane need to be non-flammable like silicon or something. The one i saw looked like regular flammable / meltable plastic.

update: I read that latex-modified thinset mortar is good enough. If anyone disagrees I would love to hear about it.

 

[webby3650]

I was in the same situation a few years back. I couldn’t find out if the membrane could handle any amount of heat. I was primarily interested in it for the vapor barrier. I ended up skipping it in the area around the stove.

 

[AlbergSteve]

I'm planning on putting down ceramic tiles on a concrete basement floor. I'm told a decoupling membrane is going to help prevent cracking due to movement because of temperature changes. Concrete floor being really cold in winter, the ceramic tile in front of the wood stove being quite warm. Anyone done this before? Does the decoupling membrane need to be non-flammable like silicon or something. The one i saw looked like regular flammable / meltable plastic.

update: I read that latex-modified thinset mortar is good enough. If anyone disagrees I would love to hear about it.

Uncoupling membrane does help with cracking of the tile due to movement. It also prevents cracks in the concrete from telegraphing through to the tile.

 

[Zoso2385]

I used an uncoupling membrane when constructing my flush hearth. I have an Jotul Oslo which requires ember protection only. I have an uncoupling membrane which is on top of the subfloor via thinset mortar and then porcelain tile on top of that. The floor in front of the stove does get pretty hot to the touch but I doubt it’s hot enough to cause damage to the membrane which is sandwiched in mortar

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[Traveler004]

I used an uncoupling membrane when constructing my flush hearth. I have an Jotul Oslo which requires ember protection only. I have an uncoupling membrane which is on top of the subfloor via thinset mortar and then porcelain tile on top of that. The floor in front of the stove does get pretty hot to the touch but I doubt it’s hot enough to cause damage to the membrane which is sandwiched in mortar

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Thanks. I'll look into that. It's beautiful btw. I love it.

 

[Bad LP]

Mine proved to be a joke and waste of time and money. I do forget what brand was used.

 

[webby3650]

Mine proved to be a joke and waste of time and money. I do forget what brand was used.

I’m curious what happened. It’s pretty awesome stuff when installed properly.

 

[EbS-P]

While I’ve never used this I like the concept.
Ditra - Heat Uncoupling Membrane
Schluter Ditra Heat Uncoupling Membrane is a polypropylene membrane with a cut-back stud structure and an anchoring fleece laminated to the underside.
It’s kinda pricy for a room sized job and getting a small quantity might not be easy. Last one my dad and I did we put cement board on 1/2” plywood and Regular mastic on the cement board.. No R value was required. They since moved and the pad and stove moved too.

I think a crack or two is better than all the tiles coming up because the latex mastic could not handle the heat. How hot are we really talking about? Does your stove need a specific R value or just ember protection? If only ember I would use latex mastic. If Rvalue is needed I would put it on cement board. I’m really at a point if there is a question about durability or quality I just choose to do it right the first time. It would take several man hours to disconnect stove and move to fix tiles if they would crack or come loose. Less than one hour and not much money to make sure that didn’t happen. Anyway just my two cents.

Evan.

 

[MTY]

Ditra, ceramic tile, BK King, 10 years, zero issues. If the cat can sleep under it, it isn't hot enough to worry about.

 

[webby3650]

The only reason I was concerned I because I never know what stove would and up on my hearth. Some of the old stoves I’ve had get the floor really cooking!

 

[Bad LP]

I’m curious what happened. It’s pretty awesome stuff when installed properly.

This is going to be kinda long but...

I got some bad advice from a guy who said to double up my bottom left plates. 2x8 on the deck then stand up the 2x6 walls. This was to allow a sort of baseline for the gypcrete pour for the RFH. Later I learned that the pour is very wet and self leveling. This of course left a dissimilar materials around the perimeter of the house and interior walls. The proper way is to just double up the bottom plates with 2x6’s.

My tile guy pointed out the fact that this detail will expand and contract at different rates. Ok. Makes sense right? He told me the only thing he could try is uncoupling membrane strips around the exterior walls.
Well they still cracked in a few spots. Mainly in the half bath on the first floor and a couple in the entry.

We told the engineers that we were using 24x24 tiles so design the floor system accordingly. The house is truly rock solid so it’s not flex. In fact the largest tile is 12x12 and the others are 12x6 and 6x6. I forget the name of the pattern.

In hindsight I should have punched the guy who I thought knew what he was talking about in the face. Ditra sheet probably would have been a better plan. We used it in other job locations but they don’t have RFH so who knows for sure. Alternatively a layer of 1/4” cement board could have been used but it would have ruined my floor elevations where the wood and tile meet. This was a detail I would have never approved.

It was after I built this house when I learned of John’s Bridge that is an awesome knowledge base of all things tile.

I was a little harsh in my first statement on being a waste. We used it at my house in MA with floor bounce. 12x24 tiles and not a single crack anywhere. It was here in Maine that had the issues and again I’ll point out what I think was a design flaw from the very first time the house was conceived.

 

[Wooden Head]

I'm planning on putting down ceramic tiles on a concrete basement floor. I'm told a decoupling membrane is going to help prevent cracking due to movement because of temperature changes. Concrete floor being really cold in winter, the ceramic tile in front of the wood stove being quite warm. Anyone done this before? Does the decoupling membrane need to be non-flammable like silicon or something. The one i saw looked like regular flammable / meltable plastic.

update: I read that latex-modified thinset mortar is good enough. If anyone disagrees I would love to hear about it.

How old is the cement floor? If it's 7 years or older it has done 99% of its movement. The heat from your stove (unless very high) should not have an effect on the tile. Use a good modified thinset. Also, check in at The John Bridges Forum for further answers.

 

[Traveler004]

How old is the cement floor? If it's 7 years or older it has done 99% of its movement. The heat from your stove (unless very high) should not have an effect on the tile. Use a good modified thinset. Also, check in at The John Bridges Forum for further answers.

The concrete floor is 50 years old. lol. i'm not worried about original settling. But up here in the great white north we get frezzing and thawing that contract and expand things yearly.

 

[Traveler004]

While I’ve never used this I like the concept.
Ditra - Heat Uncoupling Membrane
Schluter Ditra Heat Uncoupling Membrane is a polypropylene membrane with a cut-back stud structure and an anchoring fleece laminated to the underside.
It’s kinda pricy for a room sized job and getting a small quantity might not be easy. Last one my dad and I did we put cement board on 1/2” plywood and Regular mastic on the cement board.. No R value was required. They since moved and the pad and stove moved too.

I think a crack or two is better than all the tiles coming up because the latex mastic could not handle the heat. How hot are we really talking about? Does your stove need a specific R value or just ember protection? If only ember I would use latex mastic. If Rvalue is needed I would put it on cement board. I’m really at a point if there is a question about durability or quality I just choose to do it right the first time. It would take several man hours to disconnect stove and move to fix tiles if they would crack or come loose. Less than one hour and not much money to make sure that didn’t happen. Anyway just my two cents.

Evan.

It's a new stove and didn't read about any r value needed. i'm direct on cement, no subfloor. I certainly agree with doing it right the first time. I also have the unfortunate habit of spending too much on over kill because i was trying to do it right the first time and i regret it later. so it seems i'm damned if i do, and damned if i don't every time. I'll check this Ditra out. Thanks!!

 

[Zoso2385]

If no R value is required Ditra should perform fine. I have uncoupling membrane on top of my plywood subfloor and then tile on that. I was a little nervous not using any Durock or some for of cement board. I called Jotul and they said if no R value is required a piece of glass or sheet metal would technically suffice right over wood.


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