Thermal liquid screed pros/cons

[LinearPancakes]

We're looking at 50mm liquid screed for our downstairs so we can still have enough depth of insulation for the underfloor heating to work well.

 

Both regular and thermal (Thermio Plus I believe) liquid screeds are being offered. They market the thermal screed as a way to save energy, but from what I understand, yes it will heat up a bit quicker, but it will also cool down quicker.

 

I'm unsure which option is best, as I suspect the better heat retention/thermal mass could actually be better for getting a nice consistent heat and also for giving options of heating up the screed off-peak, etc.

 

We'll have 9mm porcelain tiles on top which will be adding a good amount of extra thermal mass.

 

Any thoughts on the pros/cons of thermal liquid screed over regular?

[LinearPancakes]

And by regular I mean regular gypsum based liquid screed. Confirmed this with the company.

[JohnMo]

1 hour ago, LinearPancakes said:

Thermio Plus

From the looks of it if you want to run your UFH like radiators, there may be some benefits, running like UFH low and slow, not really seeing anything it can bring to the help out.

[LinearPancakes]

Thanks @JohnMo, that's what I was thinking too.

 

So that leaves the options of Gypsum based liquid screed or Cement based liquid screed (e.g. cemfloor).

 

Anyone got experience of Cemfloor? Any issues with cracking? In principle it seems to have a few extra pros: faster drying, no laitence removal/primer needed for tiles.

[crooksey]

Gypsum liquid screed has many problems (surface laitence, drying times to name the first few).

 

You can get traditional sand and cement screeds, mixed with additives to make is strong enough at 50mm over PIR insulation (PCT XTreme is a good one) that offer a great thermal mass and heat retention.