Long term residents may recall my saga of 2016. I'm not going to rake all over it again but...
Back then there was a damp bit in the corner of the building (possibly unrelated to the leaky roof). This is what it looked like mid repair.
plaster_01 by
The Pingus, on Flickr
This is what's on the other side of that hole.
IMG_4023_01 by
The Pingus, on Flickr
You may be able to make it out here between the two satellite dishes.
2021-02-13_05-32-31 by
The Pingus, on Flickr
Now that plastic vent thingy is not an original feature of the building, and I don't know why it was installed, but I did think at the time of the repairs that it looked like an obvious place for water to get blown in. I seem to remember plonking a big rock behind it on the basis that it was handy and hoping to deflect the worst of any rain.
Anyhoo, as far as I could tell it was fine for the next few years, but towards the end of last summer I noticed it was getting mouldy down there again, and of course it's only getting worse now. It doesn't look like there's water coming in from above. It's not humid in the room - no condensation on the windows of a morning and the RH meter (situated about 2 meters away on the other side of the room) says about 40-50% which is pretty good for this time of year.
I need to do something about this, but as I'm hoping we might be able to sell this place to some other mug this year I don't want to get sucked into any major wall/plaster ripping down based type 2 fun.
I'm thinking I just need to find a way to stop water getting into the vent. Of course if it was installed horizontally then I could just fit a vent cowl over it, but it's not, so I can't.
I was thinking about asking my slate replacement operative to come round and slap some cement over it. I don't think I need to be over concerned about ventilation in the wall as when I'm upstairs in the loft it feels like there's plenty down that wall.
Think I might get away with that and some dehumidifying and antifungal wash inside?