Would you like to talk to me about air bricks..?

[everythingcrossed]

I've bought a Victorian house. It has two air bricks at level with the ground (perhaps the bottom edge is slightly below that level). We want to insulate between the ground floor joists but, when we pulled back some floorboards, we couldn't see the air bricks. When I crawled under the floor, I could feel one of the air bricks and it was level with the joists.

We really want to insulate - any advice on how should we proceed?

I made a tunnel from the air bricks to under the joists and insulated in between the joists. So long as you make sure they’re not blocked and air can move under the joists you should be okay.
On the outside, your air bricks should not be level with the ground, they should be 6 inches above it. Water will collect on the ground and pour in through the air brick. Dig holes below your bricks to improve air circulation.

The bottom of the air brick is ground level, and so the bottom of the joist is also at the external ground level?
A picture of said air bricks would help. The rule is 150mm between ground level and DPC, but for old houses 225mm is better. With regards to insulation, there are supposed to be air bricks front and back of the house for a through draft. You can insulate and just leave a bit missing so as not to block the air brick.

Ideally you need to lower the external ground level at least 1 brick below the air brick. And I'd be tempted to install a lower air brick if you want to insulate.

https://www.screwfix.com/p/telescopic-underfloor-vent-black-220mm-x-215mm/12025?ref=SFAppShare

You can use these to lower the ventilation.

Thanks so much, everyone. That periscope ventilation kit looks really useful, @NonmagicMike .

I have tried to attach a photo of my air brick but the file is too big - I think the front yard has been replaced and the level has been raised. The bottom of the Air brick is possibly slightly lower than the paving.

I think I should dig a trench like this one

Try again with the picture, there are ways to take it, then screen shot it and use that.

Thanks for the tip @HellsBalls

how do you fit these vents @NonmagicMike ?
We have a similar air brick at ground level OP

@HellsBalls were there only two air bricks installed on each property? Front and back? I’m asking to know what to look out for

OMG. That's atrocious. And cement render to the ground too!
Are the floorboards and joists pretty new? I'd be surprised if any wood will survive these conditions...

the proper way is to install in situ where your airbrick is. You’d take out the existing brick and fit the vent system in its place with a lintel on top if required. For me when I considered, I was going to just ensure snug fit against brick and secure with fasteners. In the end I just stopped the insulation a bit short of the wall so that it didn’t block anything and all has been fine to my knowledge the past two years. I have to go back under the floor next year when I refurbish the hallway so I’ll take a proper look then. May well lose some thermal benefit through not having the insulation all the way up but the room is definitely warmer than others still now that the weather is turning.

Depends how wide your house is. Usually it’s more like 3 or 4.

They are a difficult retro fit. Ideally you need access internally as well by pulling the floor up.

@everythingcrossed So yes, looks like you need to dig out a trench to lower that ground level. Initially it doesn’t need to be anything sophisticated, and letting the wall dry out takes months. Also that airbrick looks mostly blocked so you can clean that out with a screwdriver.