Thickness of screed underfloor heating

[DC1977]

Hi We are having underfloor heating put in our new kitchen diner extension, large area of approx 48m2.

It has been suggested that 100ml screed and 100 ml insulation be used, or could go with 80mm screed and 120ml insulation. Would the extra thickness of the 100ml screed affect how warm the extension is in the future?

Thanks

 

[petit_pablo]

100mm is too thick, even 80mm is at the top end of thickness for UFH screed. It will take longer to get hot and need more heat to keep it hot. Rail as thick an insulation layer as you can in then screed to between 60-75mm.

 

[DC1977]

100mm is too thick, even 80mm is at the top end of thickness for UFH screed. It will take longer to get hot and need more heat to keep it hot. Rail as thick an insulation layer as you can in then screed to between 60-75mm.

OK Ive got another couple of people telling me it is fine, but I would rather go with less thickness as will dry out quicker I presume. Can you get insulation boards that are 130mm thick, ive seen 100 mm and 120 mm....

 

[Madrab]

Depends on the type of screed, liquid or hand mixed? They have an ideal depth of around 50mm and 65mm respectively (to do with density)

A lot of it's about energy efficiency etc though. Anything over 65mm will mean the system has to work much harder and therefore use excessive energy to heat and keep warm as such it can effect the building's energy SAP rating which is becoming more and more relevant these days.

 

[DC1977]

Depends on the type of screed, liquid or hand mixed? They have an ideal depth of around 50mm and 65mm respectively (to do with density)

A lot of it's about energy efficiency etc though. Anything over 65mm will mean the system has to work much harder and therefore use excessive energy to heat and keep warm as such it can effect the building's energy SAP rating which is becoming more and more relevant these days.

I think its hand mixed, as it wont be pumped in?