Air bricks

[John Miller]

My daughter has bought a mid-terrace house which I guess was built between the wars. The front and rear walls have air-bricks set into them high up near the eves. It appears that these bricks admit rain water as there are damp patches on the inside walls around the same area.

I would like to remove them and replace with a solid brick, but they must have some purpose. The roof has no weatherdoards or soffits and perhaps they are there to ventilate the loft space via the cavity. Can anybody tell me if blocking them up is a good idea or suggest any other solution?

John Miller

[Richard Faulkner]

In message , John Miller writes

They allow ventilation and blocking them would do more harm than good. I'm not sure of the solution but wonder if some kind of shield could be built around them so that air can get in from the bottom, but rain is prevented from the top, front & sides.

[stuart noble]

I can't see that they serve any purpose in a modern house. Originally they were probably to do with ventilation for coal or gas fires, and I think you'll find they're brick lined, so wouldn't have anything to do with the loft. I used an offcut of aquapanel for the last one I did, with a couple of battens just inside the opening to support it, but bricking up might be better in exposed situations.

[Christian McArdle]

I would probably go with your guess. If true, they can be removed, provided alternative ventilation is provided, which may prove difficult if you have no soffits to put vents into.

Simply attaching a cowl over the bricks might be an alternative solution. Perhaps a small shelter bent out of some lead flashing and sealed into the mortar lines with lead sealant will stop enough of the rain coming in without blocking the ventilation. Make sure your guttering works, too. Water running down walls due to block drainpipes can be a problem.

Christian.

[sPoNiX]

Some pre-war ww2 houses had airbricks which led through both layers of the cavity wall to a vent. The idea was to provide ventilation to the upstairs rooms.

It's quite possible that the vent on the inside has been bricked up but the airbrick leftopen on the outside.

Some that I have seen had the cavity gap lined with slate...if the slate is still in place then water entering the airbrick will end up on the inner wall. Not an ideal solution.

sPoNiX

[Owain]

"John Miller" wrote | My daughter has bought a mid-terrace house which I guess was | built between the wars. The front and rear walls have air- | bricks set into them high up near the eves. It appears that | these bricks admit rain water as there are damp patches on | the inside walls around the same area.

I would be surprised if rain is actually being admitted. Could it be condensation on a locally cold patch of wall which, especially if the house has been unoccupied or poorly heated in the past, may solve themselves if your daughter moves in and heats and ventilates the place. If not, kitchen and bathroom extractor fans are probably the first step.

If there are open flued solid fuel or gas appliances exercise appropriate caution before sealing up fixed vents.

Owain

[usenet]

Not just pre WW2 houses, our house built in about 1950 had airbricks 'piped' through cavity walls. It was a very up to date house for its time (my parents designed it themselves) as it had 13A BS1363 socketed ring mains, stainless steel sink, central heating boiler and a through lounge.

[Kevin]

I think that you have just answered a question that I had. My 1936 semi has upstairs airbricks but I don't have any damp problems. I just ripped out all the old lath and plaster and replaster all the walls and ceilings. To make it easier for the plasterer I blanked off the opening with plaster board so he could skim over it. I then intended to cut out the plaster board and fit a grill but then wondered if that was necessary. I guess that it is.

Kevin

[John Miller]

Thanks to all who replied. It looks like water is definitely being admitted as a large damp patch showed up on the (newly-applied) wallpaper during a downpour yesterday. There are no corresponding internal airbricks or vents, so it is possible that these existed previously and have been blocked up - I'll investigate further. Yesterday's damp patch was accompanied by a dripping gutter outside, but we haven't been able to get up there yet to determine whether it is blocked or merely leaking. Thanks again

John Miller