Screwing through the Vapour control barrier? (Warm roof)

[Wockawocka]

I've settled on a warm roof for our kitchen extension but is it ok to screw through the vapour control barrier. It seems counter intuitive to do this?

Rubber cover
OSB (screwed through to joists)
150mm insulation
OSB
Joists

 

[noseall]

I've settled on a warm roof for our kitchen extension but is it ok to screw through the vapour control barrier. It seems counter intuitive to do this?

Rubber cover
OSB (screwed through to joists)
150mm insulation
OSB
Joists

Every VCL I've ever fitted, has fixing holes in it.

 

[phatboy]

Holes from screws holding the top deck down is pretty usual.

There are posh (expensive) VCLs available that 'self heal' around screws, like Allutrix 600, but I'd personally not bother.

If you tear the VCL, of course tape it back together well.

 

[datarebal]

Use a torch on vcl and glue the insulation , then torch on another 2mm followed by a cap sheet . No holes !
An approved system by index