UFH first floor options

[Colin Shaw]

I am building a new build and planning UFH throughout, ASHP and Solar PV. 
Looking for recommendations on how to do the UFH on 1st floor, we will be using easijoists.

was told metal plate options are poor and best was to use a screed.

18 or 22mm OSB then follow the joists with 25mm Batons and 25mm dry screed to fit the UFH piping in. Planning 18mm engineered wood floor on top but not sure if I should lay this direct in screed/batons or an additional 22mmOSB - this us what the builder suggests. I feel this will inhibit the UFH effectiveness but understand the builder is trying to make it ultra solid. 
other issue is that the floor thickness could now be 69mm plus the 18mm engineered wood which will affect sliding doors..
Anyone got similar experience or recommendations?  Thanks in advance..

[Redoctober]

Hi @Colin Shaw   Have a read of these two entries - may answer some of your questions.

 

 

[ProDave]

The "screed" idea is often known as a pug mix,  It's a sand / cement screed laid dry.  It has little strength, it is there as a heat distribution medium.  Use structural floor boards that are supported on the battens not actually supported by the screed.

 

Don't forget to size the joists to allow for the extra dead load of the screed.

 

 

[willbish]

As it's a new build your heating demand should be pretty low. You may find all your demand can be satisfied by the UFH on the ground floor.

 

This is the case in my place but I still put UFH on the first floor. Just because I don't like the idea of having to dig out electric heaters for that extreme beast from the east scenario. And I can imagine the moaning from Mrs and kids about me having built them a cold house!

 

I chose aluminium spreader plates because although they don't perform as well as a screed but they are cheaper and easier to install and for a first floor new build you shouldn't need the superior performance.

[LA3222]

I am part way through installing my first floor ufh now @Colin Shaw.

 

I put 32mm battens along the joists and then a sand/cement (8:1) dry mix down. I mixed the pug screed in an electric mixer and it mixed fine. The floor is now rock solid, harder than I thought it would be with a weak mix. Waiting for the floor to dry out enough before I put 22mm norboard floor deck over the top.

 

Loads of people on here will say you probably won't need it. I get that, I don't anticipate mine being on most of the year, but for the colder days it's there if I need it. 

 

What I did do though was put all of the upstairs bathrooms/ensuites on their own loops and I have put floor probes in too. I intend to set these off the floor temp rather than air so that the tiled floors will all be warm and not feel cold when walking bare foot.