Beam & block, screed and wet UFH

[Stewb]

Hi all,

1980s house, renovating hall, kitchen and dining rooms, knocking kitchen and dining room together. Hall circa 15m2, kitchen/diner 35m2.

Currently beam and block, 75mm screed, tile. Max 115mm clearance between top of the beam and block and the top of the lip on the external door frames so that’s all i have to play with.

The builder suggested using heat spreader panels for the UFH pipes straight on top of the current screed. I don’t want to heat the ground / have cold floors so I want the screed lifted, PIR panels, then UFH, then tiles. Tiles will be a 10mm porcelain tile.

That should be fine (screed lift/re-screed is already in the quote) subject to how much of a PITA the screed is to remove.

Two options I’m seeing at the moment having been through this forum, speaking to UFH companies, builders etc

1. Lift screed, 70mm Kingspan/celotex, 20mm heat-spreader boards with UFH piping, tile adhesive and tiles. DPC sheet below / decoupling membrane above as/if required.

2. Life screed, 50mm Kingspan/celotex, UFH pipe work clipped, 50mm liquid screed, tile adhesive and tiles. DPC sheet below / decoupling membrane above as/if required.

Overlay boards are £££

Any thoughts would be much appreciated, thanks. Also any suggestions for thin/quick drying screeds that I could suggest to the contractor.

 

[Mr Chibs]

Think I’d go for option 2, but, not sure 50mm insulation will be enough.

I’ve got 100mm and around 65mm liquid screed, and the ufh works well.
The screed people said you could get away with less Thickness i.e. 50mm as it’s more dense than standard screed.

I’ve no idea on the spreader plates, but my feeling is you need screed to convey the heat.

Don’t forget to allow two layers of tile adhesive in your calcs, one for the mat, and one on top for the tiles... plus the mat thickness.