Advice on damp corner made worse by adding Hit and Miss vent

_rix

I would be grateful for advice on what to do about the following problem. I feel overwhelmed by the potentially enormous disruption that might be created by the damp problem, so I am hoping to find out on here what degree of work might be required, and, most importantly, what sort of workman/business to contact as a next step.

Me and my partner bought a 1930s elevated ground-floor flat almost two years ago (March). I started to notice a damp problem in one corner of the bedroom at the end of the summer of the first year. The walls were painted by the previous owner (she renovated the place), and are a light grey colour. When the damp occurs, dark wet (slick to the touch) patches appear in the bottom corner and along the two skirting boards either side of that corner, as well as in the crease of the corner right up to the ceiling area.

We bought a Meaco dehumidifier which helped a lot, but I know it's only keeping the symptoms at bay, not actually resolving the cause.

So, ventilation was my next thought. The window cannot be left open overnight because it's too cold here in Glasgow for that. The window does not have a vent. But the flat was designed to have ventilation bricks in most rooms, positioned high up the wall near the ceiling. The one in the bay-windowed lounge has been covered up by a previous owner, as has the one in the study/single bedroom at the rear. There would have been one in the bedroom: because you can see air bricks on the exterior wall, it is possible to guess where the internal air brick or vent would have been. So, we recently hired a handyman to drill holes in the correct place in the wall and fit a Hit and Miss vent that we had bought online. However, there is something very wrong happening as a result: the condensation is much worse around the air vent than it was before the holes were done.

Can anyone suggest what the problem might be? I am very worried that there may be a huge leak under the floor (elevated floor might have hidden the issue for years, perhaps), and/or wet rot.

Is this a ventilation issue? Or do you think this looks like rising damp?

(As a new user I can't post links to photos of the problem... Hopefully after my first post I can.)

Doozergirl

What's on the outside of that affected wall?

If it's darker patches that turn wet, it possibly isn't condensation as that tends to attract mould. It could be though, if it dries up quickly. It just evaporates when the walls are warm.

Condensation wants warm air and walls, not just ventilation. Leaving windows open or introducing a vent in the area will cool the walls down and lower the condensing point.

You can post links to pictures elsewhere if you break the url link with a space so the forum no longer recognises it as a link. Or even just leave out the www. bit, I think. We can fix the link.

I'd be keen to see what is outside first.

_rix

Thanks for your swift reply and interest.

The building is a block of six flats built on an embankment. Here is a link to a photo I took in summer 2019, but you need to correct it: [h] [t] t p s [punctuation] [wx3] dropbox [com] /s/kvykqa1mum6c1gd/IMG_20190828_161739.jpg?dl=0

Our flat is ground right (when looking at it from the street, as in this photo).

The flats are built with a cavity wall construction. The block has a common main door and close (or, stairwell). In the close is a shared store cupboard which has bare concrete walls and floor (a tiny hatch door inside it at the back provides access to a crawl space under the building). The inside wall of that cupboard adjoins most of the length of our bedroom's external side wall. The rest of the bedroom's external side wall adjoins the stairwell wall that lies beyond the store cupboard. (I hope I am painting a clear picture for you.) So, that's what's outside one of the problem walls.

The other problem wall runs along the front of the building and meets the stairwell wall, forming the only external corner of the bedroom, which is where the damp is. The external wall is bare (no obstructions or things against it) and has been bare since the early summer of 2019.

The front of the flat is elevated about two to three feet from ground level. The two front rooms have sub-floor air bricks on the external walls, and then another air brick high up in the wall where there is a corresponding air brick on the interior wall. You can't see the air bricks in the photo above because of the angle and the height of the ferns and shrub. Those plants are growing at a distance of about three feet away from the wall of the building.

During the first year we lived here the external wall of the bedroom was covered in ivy, which blocked both the sub-floor and wall air bricks. And, the external wall had a mature yet wild shrub growing fairly deep against the bottom corner. I hired a gardener to remove the shrub and dig out all the minor weeds that had been growing against the wall. I then laid gravel down. The idea was to clear the two air bricks that served that wall and to clear vegetation to aid drying out and prevention of damage to the pointing.

So, I hope that helps!

Here are some links to pictures of the damp corner:

1. Bedroom shortly after Hit and Miss vent was installed in early December:
[h] [t] t p s [punctuation] [wx3] dropbox [com]/s/328ari1b5nebrw7/IMG_20191207_154555.jpg?dl=0

2. Showing the damp or condensation around the hit and miss vent:
[h] [t] t p s [punctuation] [wx3] dropbox [com]/s/fvtfyt3sfns5oux/IMG_20200106_073935.jpg?dl=0

3. And, showing the damp or condensation in the same corner only at the floor level:
[h] [t] t p s [punctuation] [wx3] dropbox [com]/s/668i3bjzak1vr3l/IMG_20200106_074008.jpg?dl=0

Thank you for your time and input

blackshirtuk

Doozergirl

How is the vent protected on the outside to prevent water ingress? That looks like water getting in :eek: for condensation to run down the walls like that, I'd expect to be standing in a bathroom!

The damp at the bottom:
https://www.dropbox.com/s/668i3bjzak1vr3l/IMG_20200106_074008.jpg?dl=0

It does look like damp, not condensation. Have you checked the gutters etc above during rain? It sounds like you've done the right things at ground level but that could be puddling from a leak. It would kind of explain why the vent is also causing issues itself.

Photos of outside might also be helpful.

_rix

Thank you for your help.
I'm going to contact Richardson and Starling, who are a reputable damp specialist in Glasgow.

I'm really concerned about the potential upheaval and cost, but am more concerned about the damage this is causing.

_rix

PS the vent in the bedroom creates access to a space within the cavity wall. The external air brick that corresponds in site to the vent is not covered with any good or similar. It's a 1930s red air brick. I don't know what the distance is between the two walls.

Doozergirl

Anyone who offers a free damp survey is not reputable. They are not going to offer you a free survey and then just fix a vent or a bit of guttering that costs pennies, they are going to sell you an expensive 'solution' that involves smashing the plaster off the walls and applying a waterproof render that *hides* the issue behind it for the medium term.

I've asked for photos. That's free as well, but there's not a chance of me or anyone else here selling you a thing. The solution is probably a cheap one.

Doozergirl

Do yourself a favour and have a read around this site:

https://www.heritage-house.org/damp-and-condensation/the-fraud-of-rising-damp.html