Water underfloor heating boards

Google:

polyplumb overlay

Not sure they are recommended on wooden floors though. R.

Its fine for laminate or tiles and OK for wooden boards, but expect some movement summer to winter.

TBH I am a lot less nervous about UFH now. a simple loop of pip[e between joists with kingspan underneath is probably as good as any stupid proprietary system.

Looking at the piccie, I think the Overlay system requires a solid (timber or concrete) floor to put it on to rather than being able to put it straight on top of the joists and tile on top.

I agree about putting it straight on the kingspan and forgetting all the fuss but I was wondering whether anyone had done this. I was thinking that the spreader plates would be needed to ensure you don't get cold spots and the tiles cracking. But looking at the overlay system, it seems to ignore this anyway so I guess it must be fine. Kingspan should reflect any heat up anyway so the only issue you would have is keeping the pipes as close to the ply as possible?

Do you not need reasonable underfloor insulation - which a lot of the solid floor housing stock will not have (as in any, just a freakin big lump of concrete with admittedly some heat island effect)?

Rather the reverse.

Let the pipe heat the airspace, and let the air heat the floor. More even.

A friend has 'inadvertent' UFH heating in their bathroom. The builders didn't insulate the CH pipes under it. Works a treat. :-)

The only thing to be careful of is not overdoing the temperature - but even that is not critical under wood.

Insulation is not there to reduce heat losses, in the case, its there to vector the heat upwards rather than downwards.

So its UFH as opposed to OCH ;-)

If it is the floor in contact with the earth, yes.

If its upstairs, not really.