Please help with this damp patch on my wall

[dazzler9000]

Hi all, hoping someone can help here.

I've got a damp patch that shows up maybe once a week during cold periods in the corner of my bedroom wall. I can't pin it down to days/nights when there has been heavy rainfall. The attached photo was taken in the morning after a very cold night but as far as I can tell, no rain.

I've only been in the house for two years, but I've only noticed this since I painted the walls grey, so perhaps I just never noticed when it was white?

The walls are solid plaster onto brick and as far as I can tell, the roof is okay.

I had black mould the other day and had to clean, so does this point to a condensation issue on a cold spot on the wall?

 

[JohnD]

Leak, obv.

 

[dazzler9000]

Leak, obv.

I'd 100% agree, but it happens when there's no rain sometimes as mentioned and appears to be worse when it's cold!

 

[Harry Bloomfield]

Yep, a leak. Condensation is usually worst near the ceiling. Your water mark becomes wider/wetter the nearer it gets to the floor. It may appear as much as a day or so after it has rained. Check the roof and gutters around that area. Are there any tanks or pipes near?

 

[JohnD]

Look in the loft.

And at the outside of the wall, including the roof, gutter and downpipe.

And any plumbing overflows.


Worse when it's cold? Like when the CH pump has been running for the radiators?

 

[dazzler9000]

Cheers, that's true, I hadn't thought about the delay between raining.

The previous owners had boarded the lofts floors, walls and ceilings, so it's pretty much impossible to find out anything without taking everything apart but I will have to bite the bullet and start.

Gutters are fine.

There aren't any water tanks in the loft or plumbing that I can tell.

Would you start investigations the loft or call in a roofer?

 

[dazzler9000]

I'm no builder as you can tell, but how does it work then with wall construction and solid plaster, is the water just sat on top and seeping through?

 

[JohnD]

Show us photos of the outside, right up to the roof and any chimneystacks

 

[dazzler9000]

Will do. I'll grab some photos in the morning and update the thread.

 

[dazzler9000]

Photos as discussed. I've marked roughly where the internal wall would sit in red.

The chimney is quite a distance away but can just about be seen where the ariel is.

 

[dazzler9000]

I had a roof repair done last week as there were some tears in the roof felt. This was all patched and tiles relaid.

I noticed this morning that the bedroom wall was soaking wet again and I don't even think it rained last night, although the temperature did reach -2. I mentioned before that this is noticeable after cold nights.....

I'm baffled now. Does anyone know if the plaster could be wet still and will take several weeks to dry? Perhaps overnight with humidity build up in the bedroom, it just causes warm humid air to sit on the cold damp corner of the room causing this wet patch?

I welcome some expert advice.

 

[BlueLoo]

Cheers, that's true, I hadn't thought about the delay between raining.

The previous owners had boarded the lofts floors, walls and ceilings, so it's pretty much impossible to find out anything without taking everything apart but I will have to bite the bullet and start.

Gutters are fine.

There aren't any water tanks in the loft or plumbing that I can tell.

Would you start investigations the loft or call in a roofer?

I'm no expert but this comment caught my eye.

Badly installed loft boards can stop moisture from escaping the house and you can get very damp boarding appearing.

Not so sure that you'd get that much condensation but i think lifting a few of the boards near that corner would be a good start.

If not just to check for local leaks.

Best of luck.

 

[dazzler9000]

I'm no expert but this comment caught my eye.

Badly installed loft boards can stop moisture from escaping the house and you can get very damp boarding appearing.

Not so sure that you'd get that much condensation but i think lifting a few of the boards near that corner would be a good start.

If not just to check for local leaks.

Best of luck.

Thanks, I will take a look!

 

[foxhole]

I had a roof repair done last week as there were some tears in the roof felt. This was all patched and tiles relaid.

I noticed this morning that the bedroom wall was soaking wet again and I don't even think it rained last night, although the temperature did reach -2. I mentioned before that this is noticeable after cold nights.....

I'm baffled now. Does anyone know if the plaster could be wet still and will take several weeks to dry? Perhaps overnight with humidity build up in the bedroom, it just causes warm humid air to sit on the cold damp corner of the room causing this wet patch?

I welcome some expert advice.

Depending on how wet it is, can take months to completely dry.

 

[dazzler9000]

Depending on how wet it is, can take months to completely dry.

Yes, I was wondering that. The walls are generally pretty cold to touch, guess that's because they are plastered rather than plasterboard and plaster?

Just feels like condensation hitting a cold and damp spot because of the roof leak. I'll start venting the room at night now by leaving doors open and see how it goes.

Any other ideas, keep them coming