What transition layer between tiles and chipboard with wet ufh.

Sharp Point · Oct 18, 2016

Hello peeps,
I'm currently in the middle of a full house refurb and the customer is having wet ufh retro fitted between joists on a 75mm layer of kingspan and dry screeded to top of joists, then a 22mm chip board flooring on top. What would you guys recommend as a transition layer.... plywood, warmafloor insulation etc. I'm swayed to 6mm warmafloor insulation board, would this have a massive effect on heat coming through, maybe just take longer to filter through.

cheers

Chalked · Oct 18, 2016

Why would you want to insulate on top of the floor? That would render the ufh useless.
Are you wanting to tile on top? If so it would have been better to ditch the chipboard ( another insulator). A better one would have been 25mm fermacell element flooring as it is a cement/ gypsum product, it is stable and you can tile direct.
A cheaper method is to again remove the ply and fit 12mm cement backer boards, and tile to that.
If your not tiling, you can carpet straight onto the chipboard. I just hope they have solid filled the biscuit mix, right to the underside of the board. Or it will struggle to heat the room.

Uheat – Wojtek · Oct 19, 2016

Hi guys,

I'll totally agree with Chalked.
insulation is designed to stop the heat to pass through so I would never recommend to use it on top of underfloor heating.

Is there any reason why there's 22mm chipboard required? Normally people go for 18mm which is load-bearing.
If you are tiling on top they you will be ok with UFH as tiles have got hardly any thermal resistance, you will easily get approx 70W/m2.
If you use any other floor finish you need to be careful and check the thermal resistance of each layer that goes on top.
For optimum performance we advice that the maximum combined thermal resistance, for floor coverings, of 0.2m2 K/W is not exceeded which is equates to 2 TOG.

Hope that helps.

Darren Jackson · Oct 19, 2016

I've used heat spreader plates and just laid a floating 18mm chipboard TnG floor on top then floor tiles. The customers have been very happy with the heat transfer.

Sharp Point · Oct 19, 2016

The original question is for recommendations for a transition layer, used before tiling. i'm not trying to insulate above the underfloor heating, it's just been suggested to use warmafloor to separate any thermal movement to prevent cracking/ tile lift. And I have retrofitted ufh before a a couple of times thats worked with aplomb even with underlay and thick carpet.