How to fill 150mm cavity

[Iceverge]

On 04/04/2026 at 08:35, allthatpebbledash said:

What was the cost difference between using PIR and the wool batts? Are there any alternatives to this specific brand?

 

I want to ideally beat the new wall construction u-value of 0.18w.

 

I did some calculations online using that German website I seen linked on here. Keeping a cavity at 150mm, the PIR on paper appears better. But that’s the topic being discussed here, theoretically it does. If construction doesn’t meet proper standards, how much of the supposed r value is lost?
 

PIR achieves 0.15W

Mineral wool batts gives 0.18W

 

I can build a wider wall of course and throw in more mineral wool? Then for the lintels use split lintels and avoid the catnic thingies?

 

 

 

 

 

That "mineral insulation panel" has a k value of 0.045W/mK.  try it again with a "mineral wool 035" or "hk 33" for the EPS beads.