Flat roof vent advice?

[GaryinAshby]

I need to provide cross ventilation to the roof of my new extension (cold deck). The sketch below shows the arrangement. Eaves vents are straightforward, but what can I use to provide ventilation where the roof butts up to the existing house?

Thanks

 

[noseall]

mushroom vents through the deck and membrane?

 

[GaryinAshby]

Yes, I've seen those but I was just concerned at having a join/seal between vent and membrane.

 

[GaryinAshby]

Found them! Mind, not cheap at £12.50 for a 1.2m length of extruded PVC......

 

[Roofer]

It's quite easy to form the ventilation by using an over fascia vent which you should be able to pick up for about £1.50 a metre or less

 

[GaryinAshby]

Brilliant! Thanks for that, great advice.