Laying Backer/insulation boards

[JCT]

Do these always need to be fitted with adhesive over timber chipboard flooring? Is it possible to just screw it down with washers. Here is what it says on the site. It's 6mm board.

When installing onto concrete sub floor we recommend using our flexible tile adhesive, when installing onto wooden floors we recommend using tile adhesive and/or screws and washers.

tile backer board | underfloor heating | ProWarm™

Customer wants the finished floor level to be as close as possible to the hallway floor which is carpet.

 

[Dan]

I'd have always used tile adhesive. Can't see screwing that down to the floor, then tiling on it, being a wise move.

Do they say what centres it needs to be at?

 

[JCT]

I'd have always used tile adhesive. Can't see screwing that down to the floor, then tiling on it, being a wise move.

Do they say what centres it needs to be at?

No. The quote I posted is the only instructions they provide.

 

[Dan]

No. The quote I posted is the only instructions they provide.

I'd perhaps give them a bell.

Whenever you're tiling to tile backer boards, whether insulation or not, you usually need centres close together and use screws that aren't going to rust and that sort of jazz.

 

[Dan]

To be fair I'd get that chipboard up and replace it with ply too perhaps.

If it's not on concrete I'm not sure you'd particularly need insulation. Are you using it just as a backer board so you're not tiling to the chipboard?

 

[JCT]

To be fair I'd get that chipboard up and replace it with ply too perhaps.

If it's not on concrete I'm not sure you'd particularly need insulation. Are you using it just as a backer board so you're not tiling to the chipboard?

I'm using it for both. As a backer board instead of ply and as an insulator as I was under the impression it was needed even on wood.

 

[Dan]

It's not really needed on wood. It's not going to lose heat into the wood really. It's a pretty good insulator in its self. Hence log cabins etc.

Perhaps replace the chipboard for ply and have done?

 

[JCT]

It's not really needed on wood. It's not going to lose heat into the wood really. It's a pretty good insulator in its self. Hence log cabins etc.

Perhaps replace the chipboard for ply and have done?

Replace the chipboard for ply then UFH, SLC and Tile straight on top? Can that be done? would it not need a decoupler for movement?

 

[Dan]

Yeah that's fine. As long as there's no deflection in the floor.

I wouldn't use decoupler personally. Flexible adhesive and SLC should be fine as long as you've got the ply screwed down well at 300mm centres I think it is. You might need to add noggins where they're aren't any at those points.

 

[jobdone]

What is the wattage of the mat per meter sq? Some manufacturers don't recommend going above 100 watts per m2 if straight on to timber. I always use flex ad and screws.

 

[Dan]

Of course, there's that too.

 

[JCT]

Thanks guys. Ripping up the chipboard and plying isn't really an option. Will take too long and just add cost. Insulation boards have already been purchased and floor is ready for starting tomorrow. I will install the boards using rapid set.

Here's something I've always wondered about. It's recommended to use 1 part flexi sticking the boards down on the chipboard but this would be unsuitable if tiling straight onto the chipboard. Why is ok to use spf on the boards?

 

[Old Mod]

Thanks guys. Ripping up the chipboard and plying isn't really an option. Will take too long and just add cost. Insulation boards have already been purchased and floor is ready for starting tomorrow. I will install the boards using rapid set.

Here's something I've always wondered about. It's recommended to use 1 part flexi sticking the boards down on the chipboard but this would be unsuitable if tiling straight onto the chipboard. Why is ok to use spf on the boards?

Because the idea of the adhesive is not for holding it down, it's for taking the unevenness out of the substrate you're putting the boards on to, the mechanical fixings (screws) hold the board down.

 

[JCT]

Because the idea of the adhesive is not for holding it down, it's for taking the unevenness out of the substrate you're putting the boards on to, the mechanical fixings (screws) hold the board down.

What if the subfloor is already flat?

 

[Old Mod]

You asked me why it was used, that's the reason.
To ensure the board has full contact with the floor.
If u wish to use only screws then that is your choice, as long as it fits within the manufacturers instructions.

 

[Dan]

There we go.