Help!: Heating mats on chipboard flooring

[lowstar]

Got a quote to do for 45 square m of ufh, its a new build with the green chipboard flooring already down. I thought about laying the heating mats then self levelling and tiling. Is this not appropriate to self level over chipboard. Would appreciate some info. Cheers

[Sir Ramic]

Is it a floating floor ? If so I wouldnt touch it.
I would at least over board with tile backer board before laying anything.

[lowstar]

Its a kitchen diner running the full length of the middle floor in a 3 storey house. What thickness board would you advise Sir Ramic

[Sir Ramic]

Assuming the floor is free of any deflection then 6mm backer boards with be fine or you could use Insukation boards but min I would use would be 10mm. Remember that none of these will add any strength to the floor.

[Bri]

I asked a very similar question a few weeks ago, the advice given to me was; stick and screw 6mm backers, lay mat, SLC over, then lay tiles. Job turned out mint, super solid floor. However you didn't mention if the floor was a floater, this would change everything

[lowstar]

The floor is screwed and solid. Would 6mm ply do the same job as backers, just thinking of the price of 45m2

[Sir Ramic]

No no no no No Ply. Worst thing you could do.

[Bri]

The floor is screwed and solid. Would 6mm ply do the same job as backers, just thinking of the price of 45m2

6mm ply definately no good, mainly due to it twisting and warping if it or the chipboard gets any moisture in it, use backers for peace of mind. It'll be more expensive if you have to do it twice.

[Dave]

6mm ply would not no..

You do tiling full time or a diy'er..?

[aph257]

NO. 6mm ply is a no no.

[mhtiler]

make sure to use flexible adhesives and grout,also a qualified sparky to connect ufh

[BenEyles]

If this was me i would use 6mm plyboard screwed every 8inches then lay ur underfloor heating and latex it in using a good flexible latex like bostic latex with bottle, rather than something less flexible like Ultra 2 part,obviously u would have to use flexible Adhesive and grout, but to be safe i would probably use ArduFlex 7001 which is VERY flexible and good with underfloor heating and wood.

Each to their own but never got on with insulation board etc only ever use detra matting or plyboard

And test the matting before you tile it! Its an expensive mistake if it doesnt work after you've tiled

[doug boardley]

If this was me i would use 6mm plyboard screwed every 8inches then lay ur underfloor heating and latex it in using a good flexible latex like bostic latex with bottle, rather than something less flexible like Ultra 2 part,obviously u would have to use flexible Adhesive and grout, but to be safe i would probably use ArduFlex 7001 which is VERY flexible and good with underfloor heating and wood.

Each to their own but never got on with insulation board etc only ever use detra matting or plyboard

And test the matting before you tile it! Its an expensive mistake if it doesnt work after you've tiled

so you'd overboard with 6mm ply when British Standards 15mm ply for overboarding??

[BenEyles]

I wouldn't take something you've read out a BS book as gospel!

[Dave]

I wouldn't take something you've read out a BS book as gospel!

Maybe you might not but we do.. so if that is your advice Benjamin then it is wrong.. and NO adhesive manufacturer in the uk will back your method up..

[BenEyles]

Fair comment! I've always used 9mm ply NOT the BS 15mm and never had a problem, ever! even using Vitra Flex, Ultra RSG or dunlop flex which arent the most flexible of ahesives. I did however just see the link "tiles popping up on a (9mm) ply floor" and seems that everyone is raving about boarding it instead of ply, do these boards have the same effect as ply, i.e brasing the floor and do u screw them or lay with adhesive?

[faithhealer]

Fair comment! I've always used 9mm ply NOT the BS 15mm and never had a problem, ever! even using Vitra Flex, Ultra RSG or dunlop flex which arent the most flexible of ahesives. I did however just see the link "tiles popping up on a (9mm) ply floor" and seems that everyone is raving about boarding it instead of ply, do these boards have the same effect as ply, i.e brasing the floor and do u screw them or lay with adhesive?

No Ben, these cement boards do not stop deflection in the floor. Last bouncy floor I did, fastened /re newed floorboards best I could, 1/2 " ply then hardie on top. Customer moaned about the height at first but ramped the carpet and threshold bar up and you can't tell there is an inch height difference

[BenEyles]

Yes that makes sense, but what i mean is if you have a solid chipboard floor which is solid or minimal movement are the backer boards enough to brase the chipboard joints alone or do you still have to ply the floor first, eg if you tile directly onto the chip board obviously the tiles would lift and crack on the joint between two chipboards, but is the backerboard enough to brace it?

Never had to use backer board so i wouldnt know, always used Detra or 9mm ply!