Should retrofited air bricks bridge cavity wall or not?

spencerpj · Wednesday at 1:55 PM

Hi, I have a 1970s house which only has 3 air bricks on one side of the house, so I would like to retrofit more to improve subfloor ventilation.

The company that has quoted has advised that they just need to replace bricks in the outer skin with air bricks and that this will ventilate the cavity and the subfloor. Before I continue I would like advice as to if this is sufficient as have read on other posts that the air brick should bridge the cavity to vent the subfloor sufficiently?

Thank you

stuart45 · Wednesday at 3:10 PM

They should have liners so the air goes straight into the sub floor.

jj4091 · Wednesday at 3:18 PM

You could fit these

BES.co.uk | Next Day Delivery On 15,000 + Plumbing Supplies

Ventilator / Two Brick Ventilator - Order Gas and Plumbing Supplies online at BES.co.uk. Low Prices, Free Next Day Delivery Available, 15k Plus Products in stock P/N: 12523

www.bes.co.uk

^woody^ · Wednesday at 8:59 PM

Three is enough for a typical house width.

What are you actually trying to improve, or what problem are you trying to solve?

spencerpj · Wednesday at 10:38 PM

^woody^ said:
Three is enough for a typical house width.

What are you actually trying to improve, or what problem are you trying to solve?

It is a detached house with only 3 air bricks along part of the side of one wall. The rest of the wall and the other sides don't have any so was advised that I need more on all sides to ensure cross ventilation and prevent future issues with moisture in the subfloor.

Dereekoo · Thursday at 7:34 AM

All as clause 4.14 Doc C building regs https://assets.publishing.service.gov.uk/media/5a8192a0e5274a2e8ab54b5f/BR_PDF_AD_C_2013.pdf
Don't need them on all walls just opposite ones to provide cross ventilation and avoid short circuiting

Ivor Windybottom · Thursday at 10:48 AM

Dereekoo said:
All as clause 4.14 Doc C building regs https://assets.publishing.service.gov.uk/media/5a8192a0e5274a2e8ab54b5f/BR_PDF_AD_C_2013.pdf
Don't need them on all walls just opposite ones to provide cross ventilation and avoid short circuiting

Aye, if you put them all round you can make things worse by giving the air a diagonal short-cut.

I replaced ours with ducted-through ones before the cavity wall insulation was added. For obvious reasons this is essential. If you don't have CWI then you should consider it, it makes any house much more comfortable and cheaper to heat.

The downside of better ventilation will be colder floors. Rubber crumb carpet underlay helps, or you can add insulation between the joists if you really want to.

I'm very glad we moved from a bungalow with suspended floors to one with concrete floors, far less to worry about and no creaks.

aveatry · Thursday at 12:27 PM

jj4091 said:
You could fit these

BES.co.uk | Next Day Delivery On 15,000 + Plumbing Supplies

Ventilator / Two Brick Ventilator - Order Gas and Plumbing Supplies online at BES.co.uk. Low Prices, Free Next Day Delivery Available, 15k Plus Products in stock P/N: 12523

www.bes.co.uk

I dont think that is what he needs, that is for in the wall of a room - hence Draughtbuster the OP actually needs a draft for under the floor.

jj4091 · Thursday at 12:36 PM

aveatry said:
I dont think that is what he needs, that is for in the wall of a room - hence Draughtbuster the OP actually needs a draft for under the floor.

I think you should read the original post again

aveatry · Thursday at 12:44 PM

spencerpj said:
Hi, I have a 1970s house which only has 3 air bricks on one side of the house, so I would like to retrofit more to improve subfloor ventilation.

What did I miss - he said sub floor

jj4091 · Thursday at 1:50 PM

Exactly. See post #2. I agree with stuart45 They will ventyilate without the prevailing wind causing drafts.

Ivor Windybottom · Thursday at 1:58 PM

aveatry said:
I dont think that is what he needs, that is for in the wall of a room - hence Draughtbuster the OP actually needs a draft for under the floor.

Those look like a really good idea. Might be a bit too visible for some though.

^woody^ · Friday at 1:38 PM

spencerpj said:
It is a detached house with only 3 air bricks along part of the side of one wall. The rest of the wall and the other sides don't have any so was advised that I need more on all sides to ensure cross ventilation and prevent future issues with moisture in the subfloor.

You don't need air bricks on all sides. The idea is to provide cross ventilation and that means air bricks on opposite sides. Fitting airbricks on all sides can actually reduce cross ventilation as air will tend to get pulled between those on corners, so parts of the void don't get the cross-flow they should have. Additional sides should only be ventilated if the void is complex or has obscured sections - eg a solid kitchen floor in one corner

Max 2m spacing, and first and last within 450mm of corners.

If the house is old and has not got issues now, then you wont get any in the future.

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Should retrofited air bricks bridge cavity wall or not?

​

​

​

Similar threads