Safe to block part of air brick?

newdiy123 · Posted: Sat Oct 18, 2008 3:06 pm

Hi,
I live in a 1870's terraced house on a hilly road.
On both sides of the house, there are air bricks and they look exactly like this:-

They are fitted around 3inches above floorboard level (behind the skirting). Does anyone know why??

The thing is, we get loads of draft from behind the skirting and I am wondering if I can actually reduce their air flow coming up the side of skirting by blocking top 2 or 3 rows of air brick holes. The guy at building site seemed to think so, but I rather double-check. Is this safe to do?

Many thanks

Symptoms · Posted: Sat Oct 18, 2008 6:09 pm

new - how many of them are there? Obviously they are not circa 1870, so why were they installed? - could be to vent a gas appliance in the adjacent room; could be that, whilst they appear to be 'high' the void behind may drop through the masonary to below floor level (quite common practice when there are level issues - you live on a hill). Can you lift a floorboard on the other side of the wall to check? I wouldn't block them - try to cure the draught problem by sealing the skirting/floorboard interface with a mastic.

tuckjointer · Joined: 24 Sep 2008 Posts: 63 Location: United Kingdom

You can reduce the air flow from air bricks but Symtons has a very good point with ventilation for a gas appliance. The air bricks in your picture are reasonably new and certainly weren't part of the original build. It would be wise to establish why they were installed before restricting them.

newdiy123 · Posted: Sat Oct 18, 2008 10:02 pm

hiya and thank you for replying.

There are only two bricks - one on front and one on the back..thats it.

The vent has been fitted by the previous owner, who told me that the old ones were broken/or only had a wire mesh on them.

I have lifted the skirting only a few months back and yes the vent is definately 2-3 inches higher than the floorboards.

Don't know how true this is, but I was told by a friend that in the old days they used to mess up the jobs and would simply try to cover it up using skirting etc

I have tried using caulk under and above the skirting to reduce the draft, but over time this comes away and even if its perfect, i can still feel the cold air.

Lastly I think your getting confused...I'm not planning to block the whole of the air brick, but I'm simply wanting to block 3 lines of holes at the top of the air brick, still leaving 3 lines of holes open. This will allow the air to stay underneath and not push through so much out of the skirting (hopefully).

DCC · Posted: Sun Oct 19, 2008 1:14 pm

Not an expert but from what I understand of houses of that sort of age you'll just have earth below your ground floor, and those vents are supposed to ensure the area underneath the floorboards stays nice and dry and not for venting air into the room. Sounds like yours may be one row of bricks too high?

Might be worth looking at the neighbours bricks to see if yours are different or even ask them if they get draught problems from behind the skirting.

Doc Lenny · Posted: Mon Oct 20, 2008 11:12 am

Why not fit one of these

tryitandsee · Posted: Thu Oct 23, 2008 3:05 pm

Same old problem, do you suffer the cold or the damp escalating under the floor. Both cost money although the latter costs more in the long run.

As you have one front and back, someone was trying to introduce a through flow of air, which was probably needed to rectify a damp problem. One day fuel will cost so much that buildings will evolve far beyond the standards we have lived with for so many years.

newdiy123 · Posted: Thu Oct 23, 2008 5:26 pm

surely its not reduction of airflow that does the damage? Surely its when no air comes through at all??

tuckjointer · Joined: 24 Sep 2008 Posts: 63 Location: United Kingdom

Sorry I posted a thought but I got the wrong thread

DCC · Posted: Thu Oct 23, 2008 9:47 pm

tryitandsee wrote:

As you have one front and back, someone was trying to introduce a through flow of air, which was probably needed to rectify a damp problem.

Houses of that era were built with underfloor vents from day one to avoid damp problems. The OP may have a new airbrick but its probably in the spot of an existing vent.