Dry screed on a suspended floor, minimum thickness

[snatchblock]

Hi Gents, I'm building an oak frame house in Norway, we will be using a ground scource heat pump for UFH. I have a suspended floor (wooden joists) on the ground floor, and would like to have the benefit of the thermal mass of screed rather than aluminium plates, however the locals have never heard of dry screed. I plan to have either rockwool, or kingspan foam between the joists, then a 22mm board set onto the joists whilst we are building. Once ready to lay the solid wood flooring, I will set battens, pin the pec tubing and fill the space with dry 5:1 mix sand/cement, then nail the floorboards to the battens.
My question is, do I rally need 75mm of screed over the pipes? is there any way to cut this down?
Thanks for any suggestions/comments

 

[Himaginn]

I guess no-one else has heard of dry screed over a timber floor?

 

[theprinceofdarkness]

Cor!, you have just manged to get more potential point of failure then with any other flooring system. Why not use beam and block? I think its in its name, thermal mass. You can't get thermal mass without using mass. Water is a very cheap source for this, so use big radiators.
Frank

 

[snatchblock]

Sorry to say, block and beam is not available here, hence my choice of construction

 

[jeds]

The dry mix needn't be 75mm. 25mm 8:1 mix between battens is more common.

 

[snatchblock]

Many thanks John, thats the info I was looking for!