UFH & floor construction choices

[bissoejosh]

Our upper ground floor is unusual in that it sits on both beam and block plus a small section of timber deck on posi joists. I'm quite keen to run a heat pump for UFH and need to make a final decision on floor make up. For the area on joists I'm happy either battening on the joists prior to laying the floor deck and fitting spreader plates or alternatively battening on top of the deck prior to laying the finished floor (engineered timber) again with plates. For the area above the B&B I'm less sure whether it would be beneficial to lay the piping in a screed to match the levels with the decked area or or to simply have a floating floor and spreader plates throughout. For reference the B&B area totals around 75m2 and the other 30m2.

 

I suppose my question is essentially does UFH work significantly better when in a screed compared to a floating floor or are the differences negligible?

[Nickfromwales]

Can you get insulation under the screed? If so how much ( with 65mm minimum for dry screed and 35-40mm minimum for liquid screed ). 

For the timber side I'd recommend battening the joist tops, for your returns and crossovers, and then the plates, and then 22mm P5 deck, then your engineered flooring. The P5 will help stabilise the heat delivery a bit and give you some regulation, whereas UFH direct under the flooring may be a bit of a beast to tame.  

[bissoejosh]

2 hours ago, Nickfromwales said:

Can you get insulation under the screed?

The screed will be on 200mm of EPS as a minimum. Makes sense about the P5, I've seen it done both ways but that would certainly help as a control layer.

Does the screed offer a significant advantage over a straight floating floor?

 

[Nickfromwales]

9 minutes ago, bissoejosh said:

The screed will be on 200mm of EPS as a minimum. Makes sense about the P5, I've seen it done both ways but that would certainly help as a control layer.

Does the screed offer a significant advantage over a straight floating floor?

 

It just helps to have a decent emitter TBH. 

[bissoejosh]

41 minutes ago, Nickfromwales said:

It just helps to have a decent emitter TBH. 

As I thought really. In that case I'll work on screed to match levels and then a battened joist approach rather than a battened finished floor.

 

Many thanks!

[Nickfromwales]

Just make sure the screed has fibres in it for the expansion and contraction .