Adding air bricks to a building

[OldKettle]

Hi,
I want to add some ventilation to a double brick, flat roof, extension (built in the 70s) which currently has none.

For ease of installation, I wonder if rather than installing air bricks I could just core drill and add a couple of circular vents.

Any thought would be much appreciated.

 

[Burnerman]

I have done exactly that, and closed the outside with Wickes soffit vents, stuck on with silicone.
I think they are around 70mm but it was a few years ago.
John

 

[^woody^]

You can actually buy a product that you core drill, insert the telescopic pipe liner and has an internal and external grill. Saves bodging it.

You can also get these with interval baffles to stop draughts. See Permaguard.

 

[OldKettle]

Thanks for the input.

Is this the kind of thing, Woody?

https://www.permagard.co.uk/perma-vent-standard

 

[^woody^]

Yes thats the type. There are others too under a generic name of "passive vent". The better ones have the internal baffle or membrane to prevent draughts.

 

[Burnerman]

These worked very well in a still air area for me.....no cavity ventilation of course.
John