Can it be true.....

[DHTiling]

okay then....starting from bare joists on a suspended wooden floor, how/when do we all use the uncoupler? (ideal scenario)

Timber..🙂

 

[DavieA]

What are you starting Doug,LOL

My ideal is going to be,
1. Ply floor no matter if there floor boards, chipboard etc everything but screed
2. Lay mat on all floors no matter of tile type using flexi addy
3. Lay tile onto Dural using flexi addy
4. Grout and done...

 

[Daz]

Hi DavieA,

Your scenario is ideal, however, I think you may end up pricing yourself out of work due to over-specifing.

I use a decoupler for natural stone, regardless of substrate. For most ceramic and porcelain I just make sure that the floor is deflection free.

You need to asses each job and weigh up the possibility of lateral movement and, therefore, the use (or not) for a decoupling membrane.

IMO, there is no hard and fast rule for a decoupler, just common sense and risk assessment.

 

[DavieA]

Hi Captain Slow, I realise its an expense i just want it to be right but suppose if your 100% sure of no vertical movement the matting could simply be layed on chipboard cutting cost. Dont see any need for backerboards in any floor application as they dont add strength to a floor and matting can be layed on ply if extra strength is needed or just onto chipboard if floor is sound.

Any thoughts ?

 

[Daz]

I hear what you're saying. I can fit cement boards to a chipboard floor for less than a decoupling membrane so that is the way that I choose to go, but you have to cost it based on your supply chain.

At the end of the day, as long as you are confident with the preparation work then you will be happy to pin your reputation on it.

 

[Aston]

by installing backer boards onto ply only means that there is a more stable surface on which to tile...

the joists, ply/chip board, and backerboards on top, will/can still suffer from lateral movement, therefore, the decoupling membrane does a completely different role and protects the tile against lateral movement....

in short...

no matter how thick your joists and ply are, they can still suffer lateral (side to side) movement due to the joists lying on the inner skin of the brickwork of a wall...walls contract and expand continually throught the year, intial drying out process, ground movement and weather/temperature changes..

if you put backerboards onto ply, then this is not a substitute for a decoupling matt, its simply a more stable and compound surface in which to tile upon...

as mentioned in previous posts, deflection (up and down) movement, is a different movement than lateral (side to side) when you realise that, the decisions become more straightforward...

cheers
ed

 

[DavieA]

thanks all for the advice, I realise matting is to reduce the risk of lateral movement and because of that im going to use it on every single floor i will be tiling from now on no matter of tile type or sub. The only thing that will chage will be wheither or not ply is also required and that will depend on the vertical movement/bounce in the floor.

Is that sound ?

 

[Alan.P]

Its not happening anywhere near any of my jobs and they're all south 🙂

I know people who use it over floorboards but not chipboard.

How far South are you talking, because the sites I'm busy with at the moment ( M25 and South of ) are ALL chipboard with Dural, I've told several people of the dangers but that is the spec to which we have been told to work to, and this is off 3 major developers ( I won't mention names )

Am I happy doing it, knowing it might / will fail, no. But I get paid to do it ???

 

[DavieA]

Hi Alan, glad to hear what I was hearing from topps is true. Don't understand why it should fail though, If floors solid ie no bounce and addy is suitable for use on chipboard such as keraflex then the Matt will bond well to the chipboard floor and with the Matt once layed waterproofs the sub so there is no way the chipboard will get wet and fail. I believe that's the reason chipboard is not ideal for tiling directly on to is its susceptibility to swelling if it ever gets wet and coming apart but like I said after the matting is installed floors then waterproofed and water shouldn't be able to reach the subfloor.
Maybe its because were not used to this method were unsure but if you break it down it makes sense.
I think your the only tiler Alan that has said they have layed a floor this way on the fourm, how are you finding the installs? or

 

[Alan.P]

Hi Alan, glad to hear what I was hearing from topps is true. Don't understand why it should fail though, If floors solid ie no bounce and addy is suitable for use on chipboard such as keraflex then the Matt will bond well to the chipboard floor and with the Matt once layed waterproofs the sub so there is no way the chipboard will get wet and fail. I believe that's the reason chipboard is not ideal for tiling directly on to is its susceptibility to swelling if it ever gets wet and coming apart but like I said after the matting is installed floors then waterproofed and water shouldn't be able to reach the subfloor.
Maybe its because were not used to this method were unsure but if you break it down it makes sense.
I think your the only tiler Alan that has said they have layed a floor this way on the fourm, how are you finding the installs? or

Floors are no way solid, they are nailed and not screwed down, so another problem, we don't use adhesive, we use glue. As for the installs, the first lot that I / we did have been down a year or so with no phone calls, YET. As I said, I'm not happy doing it but as part of a larger picture, I'm not turning down hundreds of houses, the guy I subbie to is aware, the builder is aware, what to do,what would you do ?