air bricks in victorian wall?

[jungle_jim01]

Hi, i'm trying to work out the construction of the victorian extension to our house. The walls are approx 250mm thick and there is at least one air brick on each elevation. Presumably this is a solid brick wall and the airbricks provided ventilation below flooring? Unfortunately at some point the floors have been concreted! argh!

Cheers

 

[Feltwell]

Is it brick construction? Sounds like a normal solid 9" wall to me. What bond, i.e. pattern, is the brickwork in?

Yes, air bricks are usually to ventilate the under-floor cavity. Unless some bodging so-and-so has taken the suspended floor out and poured lots of concrete in instead - in which case they are now purely decorative!

 

[jungle_jim01]

thanks for the reply. I can't see the brickwork as it's concealed behind some deteoriating render....that's another topic for discussion!! And unfortunately yeah...some bodger has poured concrete in! argh!

 

[Penners]

Presumably this is a solid brick wall and the airbricks provided ventilation below flooring? Unfortunately at some point the floors have been concreted!

That's exactly right. And I'm afraid your experience is far from rare. Many Victorian properties that originally had suspended timber floors (with the cavity beneath ventilated by air bricks) have now had concrete floors poured.

You either live with it or rent a Kango hammer....

 

[AMc]

You either live with it or rent a Kango hammer....

If you haven't got problems with damp on the inside of the walls then I wouldn't even consider removing it - very messy, disruptive and unpleasant. Then as you're 'renewing more that 25% of the thermal element' (a.k.a. the floor) building regulations dictate you insulate then rejoist and reboard - which might not be possible without digging out OR lay an insulated limecrete floor which will probably need excavation too to get the necessary depth.

 

[Flyfisher]

- which might not be possible without digging out OR lay an insulated limecrete floor which will probably need excavation too to get the necessary depth.

. . . and which might undermine the wall foundations as they may not be as substantial as per the modern building regs that require such a deep thermal foundation.

For these reasons, a limited exploratory excavation near one of the walls might be a good idea to find out what's really going on below, before you start hacking up big lumps of concrete from the middle of the floor. If that's what you decide to do, of course.

 

[Feltwell]

I agree completely with the "if it's not broke don't fix it" approach.

If it is causing damp then I have heard of some people who forget to tell Building Control. Apparently they put new joists in with insulation between (either solid-foam Kingspan / Celotex type or "ordinary" rolls of loft insulation supported on chicken wire stapled to the bottom of the joists) prior to laying new floorboards. Of course I wouldn't be so forgetful.

 

[Flyfisher]

Even if there are no apparent damp issues, I've heard of people installing a suspended floor over an existing concrete one and insulating in the manner described in order to create a warmer floor - taking care to ensure adequate airflow between the concrete and the raised insulation via airbricks. Also, shockingly, without involving building control.

 

[Penners]

I've heard of people installing a suspended floor over an existing concrete one and insulating in the manner described in order to create a warmer floor - taking care to ensure adequate airflow between the concrete and the raised insulation via airbricks. Also, shockingly, without involving building control.

Good heavens! Nobody we'd know, surely?

 

[Flyfisher]

I couldn't possibly say. A rum do really, although the CO didn't seem perturbed at all. Funny old world.