If paying contractors to fit insulation

[scottishjohn]

would it be cheaper to go for spray  foam to the 140mm thickness required rather than them cutting sheets to infill studding 

last time I looked at this I was told that if doing insulation yourself --then cheaper to go pir boards -- but if allowing builder to do it --then the price would be similar or cheaper to go for spray in foam after first fix 

your comments please.

[JohnMo]

Spray foam would not give the same u value as PIR board. It would be quicker.

 

Frametherm 32, which is mineral wool would fully fill the studs, way easier than cut boards. Overall although theoretically not as good as cut PIR, may actually in practice give better results. Quick and easy to install, almost zero waste. Way cheaper than both options.

[scottishjohn]

I talked with builder about that --but he says you would then need to use foam backed palster board to get  the value 

 not disputing your view on how good it would be --but it will be BC that make the judgment 

 

[JohnMo]

With only 140mm in the walls was assuming insulation board was being installed as well.

 

What is your planned wall buildup?

[nod]

No

The decision is yours Don’t let BC decide what you are doing 

Hes there to make sure you achieve the minimum