Kingspan with Membrane

19 Feb 2016
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United Kingdom
Could someone confirm if a gap is required on the wall between kingspan and membrane attached to the wall? So, I'm not asking about best practice but legal requirement.

I ask as I have 75mm joist and 75mm kingspan and no gap between membrane on the wall and the kingspan.

This is for an external single bricked garage conversion.

Last edited:
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Thanks. This is under building regs, but he didn't mention any of this and now I've got the joists
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Joists fastened to the wall and on top of the membrane. They kingspan slotted in and the. Plasterboard over the top
I've not had any coffee today so I might just be being thick! Joists go in ceilings and floors, the vertical timbers in walls are called 'studs' so are you talking about studs? Or floor joists that butt up to the wall?
Not having an air gap in theory makes for a slightly higher U value but if BC is OK with U value obtained, not having a gap should not be an issue. The fact that you are fixing the studs on to the wall and plasterboard onto the studs thus causing cold bridging I would have thought would be more of an issue but if that is what BC are approving so be it.

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