Insulation requirements for a Cold Flat Roof

[ANGLER]

What is the recommended insulation requirements between the Joist, on a cold flat roof installation.

To prevent condensation, I will be leaving a 50mm air flow gap between decking a insulation.

 

[freddiemercurystwin]

But will it be properly ventilated gap?

 

[dann09]

See: basildon.gov.uk ... document download ... Part-L Insulation

 

[tony1851]

What is the recommended insulation requirements between the Joist, on a cold flat roof installation.

To prevent condensation, I will be leaving a 50mm air flow gap between decking a insulation.

It's usually around 125 -150 mm Kingspan or equiv.
But - yes - mind the gap.

 

[ANGLER]

The Gap will be vented at both ends (front via facia 25mm. Rear into existing pitched roof space.
I was going to use 100mm Kinspan, then top up the 8x2 C16 joists with normal loft lay insulation.


Thanks for all your help.