Xtrathem cavity wall insulation

[SarahG]

Our architect has spec'd the following cavity wall insulation:

 

100mm. cavity with 95mm. Xtratherm Cavity

Therm CT/PIR insulation plus 5mm. residual

cavity

 

Just wondering if anyone knows a good alternative. One of our potential builders seemed concerned about the price of this one, we really don't want to make the walls thicker just to fit in some cheaper insulation. So just wondering if anyone knows any suitable alternatives.

 

One of our contractors has quoted us for Celotex Thermaclass 21 Full Fill Cavity Insulation 90mm instead, is this a good alternative? We could potential get one with a slightly lower u-value and re-run the SAP report I guess.

[Dave Jones]

recticell

 

[Iceverge]

Thicker walls are the only way if you want to stick to a masonry cavity wall.  A 150mm cavity with full fill cavity batts like Dritherm 32 or EPS Beads would be the same U value of 0.22. PIR boards are almost impossible to fit correctly in a cavity wall, even with well intentioned builders. I wouldn't consider them on those grounds alone.

 

Have you considered SIPs or timber frame if thickness is really such an issue? 

 

 

 

 

 

 

 

 

[Johnnyt]

We were specced Kingspan Kooltherm k106 and used cavitytherm as the alternative.

Brickies had never seen it before but said it was good to work with as it interlocks no taping and no retaining disc required, dedicated slots for wall ties.

Remember to put a vertical dpc in the corners