When Do You Uncouple?

[Flintstone]

I have used uncoupling mats before, but not extensively. It's only maybe the last 18 month or 2 years that my local tile shop has stocked them.

When do you personally use an uncoupling mat and when don't you? Materials and substrate.. I understand what lateral movement is, but I have seen people using mats on solid floors I think

 

[Callum Curwood]

I normally go with it when the floor transitions between two different substrates or if I've got a good few door ways to pass between as it relives the stress which doorways do to remove the chance of cracking in the future. Normally if I'm just on 1 substrate the I prep that as needs be

 

[One Day]

I don't always use them. Heated floor of a large size, yes. Small heated floor, not unless I'm fixing some weak stone. Fresh screed, yes. Anhydrite screed, always (at least until I'm convinced by gypsum adhesive). Typical thought process is highlighted by a job I'm soon taking on... 300sqm of high quality porcelain onto heated anhydrite screed. In theory i can tile direct using gypsum adhesive. Will i risk 15k worth of tiles popping? No way. Its ditra for me.

 

[Dhtiling]

Wood subfloor or lots of windows. Almost all my floors are over wood, so basically every job I do. Things move at different rates and it seems like cheap insurance. An added benifit is most membranes are lighter and easier to work with than hardi.

 

[hmtiling]

large pumped(gypsum) heated floors definitely

 

[Flintstone]

Wood subfloor or lots of windows. Almost all my floors are over wood, so basically every job I do. Things move at different rates and it seems like cheap insurance. An added benifit is most membranes are lighter and easier to work with than hardi.

This is one thing I don't get, what's wrong with over boarding with hardie or no more ply. It's solid and there is not gonna be any lateral movement. Why use a membrane instead ?

 

[Stef]

I only decouple when I'm using stone.
I see someone has stated that they use it to go between 2 different substrates.
That's not what Ditra is designed for, there should be an expansion join in the tile face following through from the substrate.
Also through doors you should have a break in the tile between joining rooms.

 

[J Sid]

I've been using Ditra for about 15 years now.
When do I use it.... over all wet ufh, under all stone, over all wood and over green screeds.

 

[Flintstone]

Over all wood, would you use it on a 4m bathroom floor. Floorboard, hardie, then 300x300 porcelain ?

 

[Stef]

Over all wood, would you use it on a 4m bathroom floor. Floorboard, hardie, then 300x300 porcelain ?

I wouldn't as I see that as over kill tbh.
If you look at the American market almost everyone over there uses a decoupler on every substrate.

 

[J Sid]

Over all wood, would you use it on a 4m bathroom floor. Floorboard, hardie, then 300x300 porcelain ?

If floor boards are solid then I would Ditra, even a 1m2 floor, if not so solid then I would HB it

 

[Flintstone]

I still don't see the benefit of it instead of boarding

 

[J Sid]

A lot quicker to prep the floor than HB if sub floor is solid

 

[MW Smith Ceramics]

Personally I would never ditra onto floorboards as this won't stabilise the floor, even if it is solid it's too many separated peices of wood for me, I've always over boarded with Hardi backer or no more ply 6mm or 9mm if possible glued with polyurethane adhesive and screwed......bombproof

 

[MW Smith Ceramics]

I don't always use them. Heated floor of a large size, yes. Small heated floor, not unless I'm fixing some weak stone. Fresh screed, yes. Anhydrite screed, always (at least until I'm convinced by gypsum adhesive). Typical thought process is highlighted by a job I'm soon taking on... 300sqm of high quality porcelain onto heated anhydrite screed. In theory i can tile direct using gypsum adhesive. Will i risk 15k worth of tiles popping? No way. Its ditra for me.

That gypsum based adhesive scares me too impish!.....don't mind laying the decoupling membrane with it ( Bal rapid mat mostly ) then flexi cement based addy

 

[Stef]

That gypsum based adhesive scares me too impish!.....don't mind laying the decoupling membrane with it ( Bal rapid mat mostly ) then flexi cement based addy

I've done a few gypsum floors & give me them any day over a cement screed.
Anhyfix for adhesive & as long as all rules are followed then there's nothing to be worried about.

 

[MW Smith Ceramics]

I've done a few gypsum floors & give me them any day over a cement screed.
Anhyfix for adhesive & as long as all rules are followed then there's nothing to be worried about.[/QUOTE

I've done a few gypsum floors & give me them any day over a cement screed.
Anhyfix for adhesive & as long as all rules are followed then there's nothing to be worried about.[/QUOTE

Are gypsum based adhesives recommended with British standards??.....I'm sure even if it comes to annhy screeds then British standards recommend priming then cement base addy

Can any of you technical gurus confirm???

 

[Stef]

I'm not sure what British standards state but why take the chance of putting cement in contact with gypsum when they are not compatible unless you create a barrier between the 2?

 

[MW Smith Ceramics]

Totally see where you are coming from there Stef........it just baffles me why gypsum based adhesives are not mentioned within British standards regarding tiling onto gypsum screeds, so you have Ardex, Bal & Mapei that all recommend priming then using cement based addy and this is British standards they follow, so regarding gypsum based adhesive who makes the rules

 

[White Room]

Totally see where you are coming from there Stef........it just baffles me why gypsum based adhesives are not mentioned within British standards regarding tiling onto gypsum screeds, so you have Ardex, Bal & Mapei that all recommend priming then using cement based addy and this is British standards they follow, so regarding gypsum based adhesive who makes the rules

They probably haven't caught up yet or haven't a clue about usage of it....

 

[Stef]

They probably haven't caught up yet or haven't a clue about usage of it....

Probably don't know about it.
I've only done one anhydrite floor with a cement addy, I gave it 4 or 5 coats of primer & im still paranoid about it.
It's still stuck solid but I wouldn't just rely on 1 or 2 coats of primer as manufacturers state as I don't think your creating that barrier between the 2.
Anhyfix is a superb addy & sticks like the proverbial.

 

[Flintstone]

I struggle to see the use of uncoupling unless your perhaps using fragile stone tiles. As said by some one else, I wouldn't feel happy laying it over floorboards when you could board it instead which would probably take a fraction longer to do

 

[One Day]

But if you don't need to add strength, and only need protection from lateral stress, why bother over-boarding?

 

[Stef]

Good discussion from both sides.
I've started using more thermal boards than Hardie as the foam in the boards will slightly decouple the substrate, this is only my view don't take it as gospel,
I used Ditra on caberdeck flooring & had problems with a bit of grout cracking, Ditra fixed with af200, I couldn't overboard as we were tight to the front door.
In America they overboard with OSB then fix Ditra to everything.

 

[J Sid]

I struggle to see the use of uncoupling unless your perhaps using fragile stone tiles. As said by some one else, I wouldn't feel happy laying it over floorboards when you could board it instead which would probably take a fraction longer to do

I have in the past laid no more ply over boards and had It fail, the boards cracked along some of the wood joints..... Hence I use membrane now.
I would add I feel HB is a better product than NMP and prefer the fixing method for HB, feel it gives a stronger finished floor.

 

[Dhtiling]

Here where I live everything is wood subfloor, so most everything gets a membrane. If a floor needs added strength we do that with plywood then a membrane. Ditra or any other product is nice because it is lightweight so easier on the body to install. Are membranes overkill in most cases, sure, but people who call for work have seen the marketing and ask for it usually.

 

[Flintstone]

A high amount of regular Joe blogs customers aren't over the moon about the cost of boarding never mind adding a mat on top. Would probably loose loads of jobs if I insisted on both of those things. Boarding for me bridges all joints in floor boards etc with something solid.

 

[One Day]

If a potential customer won't listen to and accept my advice on how a job should be done, then they never make it to 'customer' stage. Why bother if they won't play it your way?

 

[Flintstone]

I agree with you totally. I was referring a bit to dhtiling saying he puts a mat on every wooden floor. - no need.

 

[Flintstone]

I'd like to know how there can be lateral movement in nmp boards glued together

 

[Dhtiling]

I agree with you totally. I was referring a bit to dhtiling saying he puts a mat on every wooden floor. - no need.

At the end of the day, I am charging the same price for cement board or membrane. It is cheap insurance in my mind since wood moves and tile moves at different rates. Also you guys have courses and trainings for tiling, many guys here don't and there are a lot of failures because of improper installation, people see why and it is usually cement board or hardi installed wrong, so customers who research things feel more comfortable paying for the mat.