To insulate my loft space I was planning to put kingspan in between the rafters, 150mm rafters, 100mm-120mm kingspan with a gap above to let the membrane breathe. However kingspan is cut by hand, not very well, and it's not a good fit in many places. So I did a small area only and then stopped. I attach a photo. To achieve the necessary U-value I also have to have insulated plasterboard, 37mm (25mm insulation + 12mm plaster). That will close all the gaps too I suppose.
I was then approached by a spray foam loft insulation company for my loft. They tried to explain how the foam is breathable so I do not need a gap between it and the felt. Anyone has experiences with this insulation technique?
I was then approached by a spray foam loft insulation company for my loft. They tried to explain how the foam is breathable so I do not need a gap between it and the felt. Anyone has experiences with this insulation technique?