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Insulation thickness/air gap in flat roof.

I have 125mm joist supporting a new flat roof, what thickness insulation do I need to have the correct air gap? The span is 2.5 meters.

Thank you

1 Answer from a MyBuilder Roofer

Best Answer

Hi Dave the correct insulation for 125mm joist is 100mm max leaving a 25mm air gap.


Answered 18th Oct 2017

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