hardi and decoupling

[kevin67]

can you lay a de coupling membrane ontop of hardibacker? im laying trav tiles in a kitchen with ufh, just wondering if this is ok

cheers

[Bri]

Whats the substrate?

[kevin67]

its chipboard over joists.

[Bri]

Do you know the thickness of the chipboard, and is it solid and free from deflection?

[kevin67]

yes its 18mm chipboard. its solid and free from deflection. i had an issue with the plumbers who put in the ufh as they put 18mm chipboard down then 18mm ply so i told them that the heat wouldn't get through to the tiles after advice from here . so they took up the ply and i had a look at the floor and its all new chipboard and its solid. i thought that 6mm hardi with a de coupling membrane on top of the chipboard would be ok but want to check if it is ok

[Bri]

So long as everything is solid and the hardi is stuck down with flex adhesive then screwed, then the de-coupler is stuck down with flex adhesive I forsee no problems.

[kevin67]

thanks for the help brian. the customer put the ufh on and there was good heat from it without the ply so think it would be ok with the hardi and de coupler, but wanted another opinion

cheers mate

[DavieA]

Hi Kev, How did you get on with your job? have similar coming up and had come up with same plan.

[kevin67]

Hi Kev, How did you get on with your job? have similar coming up and had come up with same plan.

got on fine doing it this way, also i called back into the job a few months later and everything was fine

[DavieA]

Cheers for the help and glad it went well.

[impish]

Why use HB at all there? Wouldn't you be better with marmox glued and screwed (using washers)?
James Hardi say there is no thermal advantage using HB over a plain old cement floor. It absorbs heat as well as cement and does nothing to insulate.

[Gall.B]

Kev, Who do you find best for supplying decouplers etc in our area ?

Hail Hail