Options to reduce insulation thinkness in loft conversion
Discussion
We are soon starting a loft conversion and the architect has spec'd 150mm of rigid insulation (kingspan etc) between joists and 37.5mm Kingspan k18 or similar (plasterboard + rigid insulation) as the finishing over the top of this.
Space is a bit tight are there any options other than the kingspan k18 that will offer the same u value but not as thick?
Space is a bit tight are there any options other than the kingspan k18 that will offer the same u value but not as thick?
It's been a real war of attrition this whole area.
The original spec was 100mm in between the rafters with 50mm air gap at sarking, however as the roof joists terminate in the wall head there is no eaves gap or air flow. The BC first requirement with this was to fit a roof vent to every joist space - this would have made the roof look ridiculous with 20 vents in a 9m run.
Anyway we found a new solution and this is the last issue I want to address so yes I am carefully considering it as I do worry about interstitial condensation!
The original spec was 100mm in between the rafters with 50mm air gap at sarking, however as the roof joists terminate in the wall head there is no eaves gap or air flow. The BC first requirement with this was to fit a roof vent to every joist space - this would have made the roof look ridiculous with 20 vents in a 9m run.
Anyway we found a new solution and this is the last issue I want to address so yes I am carefully considering it as I do worry about interstitial condensation!
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