UFH Specific Insulation or is "Standard" Board ok?

[Woody12]

I've spent the last week trying to research, to no avail, whether we need to use UFH specific insulation (i.e. FF4000) under our UFH or if standard boards (i.e. GA4000) will be ok?

Are UFH specific boards just marketing gimmick by the manufacturers to make you spend more money, or is there a general reason to use them?

Floor construction:

75mm liquid screed
Vapour Barrier
100mm insulation
Vapour Barrier
Concrete
DPM
Hardcore

Any pointers would be much appreciated.

 

[ALEC1]

what's important is the heat loss.. how you get there isn't really that important..

it also depends on the ratio of internal wall to floor space! but 75mm of king span normally fits the bill

 

[Norcon]

For your set up a marketing gimmick.

With a lot of these boards you actually lose heat transfer between the pipe and screed as the pipe is half buried in the board.

Clip rails is all you need which will suspend your pipe and allow the liquid screed full contact on the entire circumference.

This image will give you a general idea.
http://www.homebuilding.co.uk/advice/DIY/wet-ufh

Only have the rails closer so that the pipe does not touch the insulation and use the double meander layout pattern.
A lot of cowboys in the ufh business.

 

[Woody12]

Thanks chaps. I'll order the standard boards.

Cheers!

 

[roguetrader]

Make sure you fix your pipes down properly, liquid screed is a bastard for floating your unsecured pipes.

 

[doitall]

Make sure you fix your pipes down properly, liquid screed is a b*****d for floating your unsecured pipes.

And the trays and insulation