Air brick inside clothes wardrobe needs filling in - what do I use?

[Monique Castellani-Kraan]

Hi all, could use some input on this because I'm a bit of a novice and need to make sure I'm using the right tools for the job!

Our house was built in the 1940s and we've lived there for almost 30 years, and little did we know there was a badly filled-in air brick inside my build-in clothes wardrobe. In recent years I wondered why I had such a bad clothes moth problem and why my clothes smelled fusty.

The air brick is 6 ft above the floorboards, directly inside my enclosed wardrobe. It is in a contained space consisting of only my clothes wardrobe and bookcase inside my bedroom. Photos here.

It seems the previous people did a bodge job and filled it in from the inside using only plaster filler, so of course over the years the plaster has deteriorated and crumbled - and has now had an explosion of mould growth that spread all over the walls and ceiling in the upper storage section of my wardrobe. Had to absolutely blitz it with bleach and throw a load of stuff away. (and for anyone wondering how I didn't notice for so long - I use the upper level for storage so I couldn't see what was happening until it was too late)

So needless to say this air brick needs filling in because of its ridiculous location. Now the question is what do I use to seal this flipping thing up for good so that this doesn't happen again?

It would have to be sealed from the inside as this is an upstairs room. Would it be feasible to scape off all the old stuff, seal it up with repair cement, then re-plaster and paint? Any help and tips would be greatly appreciated. Brands and recommended products especially. Thanks! :)

[Murmansk]

I think I'd hack off all that plaster/filler to the point where you can see the holes in the air brick. Then clean out the first couple of centimetres of each hole and fill with silicon sealant. Then plaster over it .

[alan_m]

Is there still an air brick on the outside of the house or has that been filled in as well

Perhaps when filling in the air brick the cavity has been breached giving a path for moisture to travel from the outside wall to the inside wall. Is you house built with cavity walls or is it solid brick?

[alan_m]

Is the photo after the bleach treatment?

Don't overlook that the filled in airbrick may not be the problem. You may have a leaking roof or gutter above your wardrobe causing the problems on the ceiling and/or walls. Water then could be running down inside a wall cavity until it reaches the porous air brick fill and then is coming back to the inside of the wall. The fill material may be acting as a sponge with no brick or block behind the surface coat to stop water penetrating.

Check for any cracked tiles or slates above the area or any water staining on the exterior wall in the location. Check that your gutters are not blocked with leaves or moss in that location which could cause water to overflow the gutter.

If its a filled in air brick where is the water coming from i) condensation? ii) a hole in the outside of the wall that hasn't been blocked off? iii) from the roof iv) from the gutter

Perhaps the original purpose of the air brick was to prevent condensation occurring?

[Fredxx]

Clearly one or more of those walls is an outside wall. It is therefore going to be colder than the room so condensation will form on these walls.

Given the passage of time, apart from the refilling of the airbrick, you need ventilation between the room and wardrobe. I would suggest a series of holes in the bottom and top of the wardrobe between that and the bedroom.

[Brian Gaff (Sofa]

I find this a little odd. You need air bricks to stop condensation in this house, but I guess diverting it to the main room with a duct cannot be done? Brian

[Chris Hogg]

The air-brick serves a purpose, which is to allow damp air in the room or wardrobe to escape. Has the wardrobe always been there, or is it relatively recent. There is damp air trapped in the wardrobe, condensing on the cold outer wall and encouraging mould growth.

The damp air is most probably coming from inside the house. Are people sleeping in that room when before it wasn't used? Have you started drying washing indoors - in that room for example? Have you started using a portable gas or paraffin heater in the house, that would drive up the humidity? If so, stop using it - they give off lots of water vapour. Open up the air brick to allow it to do its job. Get a dehumidifier and run it in that room.

[Jim GM4DHJ ...]

I would have thought your problem would get worse without the air brick ......

[Martin Brown]

Looking at that picture I am more concerned with the corner ceiling which looks to be the source of the walls dampness. I think the air brick is a symptom and not a cause. Although the previous attempt to fill it may have bridged the inner and outer walls leading to problems.

Which direction does the offending wall face? Into the prevailing wind?

I'm not sure that opening the air brick might not at least partially solve the problem by allowing some exchange of air with the outside.

The way that the steel bracket has rusted suggests that the entire wall is damp and the inside of the wardrobe too. The edges of the impermeable air brick are merely acting to focus the dampness.

[polygonum_on_google]

Some years ago, I lived in a house which was massively over-supplied with similarly position air vents. The excess air flow, especially cold, wet air in winter, made what was otherwise a very dry and reasonably warm house feel cold and unpleasant.

One room was particularly bad and, as were switching things round, using it as a home office meant it was occupied much of the day. So the cold air was far more important.

As a strictly temporary measure, I bashed a bit of Celotex into the hole on the inside leaf. Covered with a bit of plasterboard - just pushed in place. Then slapped on some sort of plaster-based filler (I really cannot remember what it was). Made an acceptably smooth and flat finish - sufficiently good that our eyes were not drawn to it.

Some time later, as that had worked well, I did the second air vent in that room. Followed by three others over the next year or two. All using much the same technique.

Given the relatively poor fit of the double-glazed windows, there was still plenty of airflow but the improvement was huge.

Around ten years after doing the first one, we moved on. All air vents still filled adequately, untouched other than redecorating.

But you have got a ceiling problem. And, I suspect, condensation. Is the attic insulated properly? Is there rain ingress?

[Monique Castellani-Kraan]

No leaky roof as far as I know, we did recently have the roofers round for maintenance. Had a leaky bay window that needed the lead flashing repairing. I am wondering if Alan is right and condensation is the cause - we have had an awful problem with it in the house in recent years and ended up needing a dehumidifier.

The mold first started round the vent then travelled upwards to the ceiling (the photos are after I bleached the everloving hell out of it). Thing is, this air brick has been blocked up for over 30 years. Only in the last 5 or 6 years or so has that mold problem appeared. The wall is north-facing and it's solid brick. Yeah diverting air into the room cannot be done sadly, not without tearing off the wardrobe doors or ripping out the panelling anyway. Don't have the tools for it either.

The air brick is untouched on the outside of the house. The vent isn't metal it's brick, what you can see in the photos is the brick showing through underneath the plaster.

I posted around on other forums last night too, I've been given so much conflicting advice by this point I'm just confused. xD Some people saying block it up some people saying open it up. So I'm looking into removing all that plaster and getting an adjustable vent cover for it instead, we'll see how it goes from there. If problems with it persist I'll block it up :) Just a bit concerned that it's going to ruin my clothes and books inside that wardrobe if I open it up which is why my first concern was sealing it up properly.

Thanks for the advice everyone, I really appreciate your help!

[alan_m]

Possibly because its hard to diagnose the problem from a distance and there could be more than one possible cause for the damp. Some people may assume one cause and one solution whilst other may assume a different cause and suggest a different solution.

xD Some people saying block it up some people saying open it up. So I'm looking into removing all that plaster and getting an adjustable vent cover for it instead, we'll see how it goes from there. If problems with it persist I'll block it up :) Just a bit concerned that it's going to ruin my clothes and books inside that wardrobe if I open it up which is why my first concern was sealing it up properly.

If the problem hasn't been evident for the previous X years what may have changed? Could it be that what has been stored in the area has been packed in so tightly against the wall and ceiling that it is trapping the water in the wall/ceiling. Perhaps in the past a gap between the wall and stored material allowed any minor dampness to evaporate to atmosphere?

If you do open it up and put an adjustable vent on the inside place a thin sheet of open cell foam behind the vent. Often open cell foam (usually black in colour) can be found in the packing of household electrical items but also available on Ebay etc. This will help stop a gale blowing trough the airbrick when the wind is in the wrong direction.

[Monique Castellani-Kraan]

Just removed the plaster to reveal (dun dun dun)... an extremely rusty, ancient metal vent cover. Unsure how to proceed here. Any advice? Photo:

[The Natural Philosopher]

Ther are two methods of controlling condensation - one is high airflow of low humidity air plus heating = airbricks and heaters and energy, and the other is to simply cover the cold wall in an insulator, so it isn't a cold *surface* any more.

I had a kitchen built out of single 4.5" brick with an outside wall.

Cork tiles solved the condensation completely

[The Natural Philosopher]

Photo as usual unviewable on Linux.

Fill it all up and cover the wall with plasterboard and celotex dot and dabbed in place.

[newshound]

1940's could mean it might or might not have cavity walls. That could make quite a difference in what remedial work is needed.

[Fredxx]

Have you considered a positive move to Windows?

The photo shows discoloured painted wallpaper on the ceiling and discolouration at the blocked up vent.

It may solve the problem but seems overkill and not easy task in a built in wardrobe.

I suspect the floor of this house is unheated from being unoccupied. That, a wardrobe on a cold corner and a lack of ventilation are the more likely culprits.

[Tim Lamb]

A rusty cast iron job.

Vents part way up walls here have been installed to meet draught regulations for chimney vented gas fires. Sleeved so there is no intended link to any wall cavity.

ISTR mention of this now being used as a bedroom. Clearly changes have been made and it might aid advice if more were known about the building history.

The wardrobe/cupboard appears to be a later addition perhaps due to a change of use.

My experience of fitting a wardrobe to an insulated modern cavity wall is DON'T DO IT!

Black mould at high level on walls is an indication of too much atmospheric moisture, too little room ventilation and insufficient heat input.

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[Jeff Layman]

Something is wrong with your setup. I have no problem seeing the picture using Pale Moon 28.16.0 or Firefox 84.0 (Linux Mint 20.0 x64).

[Jeff Layman]

Or a dehumidifier. But your first method or a dehumidifier will cost money every time they are in use.

Don't they make the kitchen a bit on the dark side? I assume they can be painted, but could they be tiled over instead? --

Jeff