Extension and existing cavity wall

[Millwright]

Hi.

I'm having an extension built onto the rear elevation of which the existing wall is a cavity wall, with two cavity vents on the outside wall one course below the damp proof course. Original build is suspended vented timber floor.

Should these vents be 'extended' through the extension, such as ducting through inside the extension concrete floor leading to vents placed in the new extension wall?

Thanks.

 

[noseall]

Yes, all existing sub-floor vents must be extended through to the new outside wall.

Add more if venting at present is inadequate.

 

[freddiemercurystwin]

Have a scroll through this thread for some pics //www.diynot.com/diy/threads/garage-floor-building-control.171482/

 

[Millwright]

Thanks.

 

[Millwright]

I had a read of that thread. I notice tht the cavity vents are extended through the concrete floor. Our concrete has already been poured, we have a depth left of about two courses of bricks to fill with 100mm celotex and then screed. Is a channel in the celotex normally permitted or running the vent extention in the screed?

 

[noseall]

Go through the celotex layer.
It would have been better to have done this lower down as you may come smack up against a joist when knocking through to the existing floor, depending how the joists are orientated.