Pecilastic on electric underfloor heating - TilersForums.com

[Cookerooby]

Hi,
Anyone know if you can fix Pecilastic (or similar) to electric underfloor heating mat that has been covered in levelling compound? Have a situation where the join in two insulation boards coincides with a join in timber floorboards below it. It’s a plank tile floor and the planks will be running at right angles to the join in boards described. I can see a hairline crack in levelling compound and am concerned about the planks cracking.
Many Thanks.

 

[Dan]

Needed an expansion strip where the two floors met.

Oh no wait.

So we have a timber tongue and groove floor, then insulation boards, then underfloor heating mat (cable), then self levelling compound?

What insulation boards were used? And what were they stuck down with?

Any pictures of the job?

 

[J Sid]

I'll be concerned with the ufh wire, is it running across the joint or are the two areas independent of each other as they should be with a expansion joint over the two floor intersection?

 

[Cookerooby]

Photo shows the join of of two 10mm Marmox boards. This join is directly above a join in the floorboards. Insulation board is stuck with Setaflex adhesive and also screwed down.

 

[Dan]

I might have read that wrong mate.

So it's a join in the timber floor. Matching a join in an insulation board.

Edit: posted at the same time then.

Is the wood floorboards or that tongue and groove chipboard stuff?

Then next question would be is the marmox meant to have a tape over joins? And it might just be that you've lost some SLC down the join and some adhesive there would be fine?

Something seems weird with it but it's beyond my scope mate so I'll stay out of it now.

 

[Cookerooby]

I don’t normally tape the joins of insulation boards and never had a problem. I might be worried over nothing, but I got a bit alarmed when I noticed that SLC had disappeared. I don’t think I would have left that big a gap between boards when fixing them and am concerned that gap might have developed by slight movement in the two floorboards in the time between insulation boards were fixed and SLC applied which was a couple of weeks.

If I can lay pecilastic over this join then I think it’s a sensible precaution against the tiles possibly cracking, I’m just unsure of the ‘rules’ about laying any anti fracture mat over UFH cables.

 

[Dumbo]

You're joints should be taped as per recommendation they should also run at 90 degrees to the orientation of the floor boards , are they screwed down or just stuck ,
I've run membrane over ufh , no problems , why should there be , but they may ask for more depth of leveller first before laying membrane

 

[J Sid]

I'm out

 

[Andy Allen]

I'm out

is it raining?...

 

[J Sid]

Work 😭🤣🤣

 

[Cookerooby]

Boards are laid at right angles to floorboards and are screwed as well as stuck. The join in the floorboards below are where the ends of some floor boards meet and also where some have been cut to (I presume) carry out plumbing/electrical work. That’s why gap is fairly isolated and not spanning the whole room.
I’ll go with a membrane, anyone know of (if any) recommended minimum depth of SLC above UFH cables?
Cheers.

 

[Dumbo]

Boards are laid at right angles to floorboards and are screwed as well as stuck. The join in the floorboards below are where the ends of some floor boards meet and also where some have been cut to (I presume) carry out plumbing/electrical work. That’s why gap is fairly isolated and not spanning the whole room.
I’ll go with a membrane, anyone know of (if any) recommended minimum depth of SLC above UFH cables?p
Cheers.

Depends on membrane , speak to the manufacturer if your chosen product .