Quinn therm.

[trialscot]

Hi,
The working drawings for our extension specify minimum 80mm Xtratherm or equal between 145x45 timber frame wall studs.
I can collect this from about 100 miles away for nearly £29 per sheet, or get Quinn therm delivered at under £24 per sheet.
The local TP and Jewsons only do 75mm insulation sheet and both have warned me that "the irish stuff" is no good.
Wall construction is 100mm dense block with 19mm roughcast render, 50mm cavity, breather membrane on 9mm ply sheathing on 145x45timber frame, 12.5mm foil backed plasterboard. The Quinn therm calculator seems to exceed the required u value of 0.27 but I'm not very sure about all this.
Any comments please?.

 

[jeds]

Xtratherm has a tiny bit better thermal conductivity (but not enough to make a difference to the U-value over 75 or 80mm) and it is very slightly denser. I suppose you could say Xtratherm is slightly better but functionally the higher density means nothing and the thermal performance will be the same. Price is by far the most significant factor.

 

[hotrod]

Sheffield Insulations have got a branch in Inverness. They stock Xtratherm. I would take any "advice" the staff at TP and Jewsons give you with a pinch of salt, especially wrt to insulation efficacy and U-values etc.

hth

 

[trialscot]

Many thanks for the help guys.