Wet patch where ceiling meets wall

3figures

We have been getting damp patches in one of our bedrooms on and off for the last few months but it was got particularly frequent in the last month or so. It is nearly always where the wall and ceiling meet and was in one patch but other patches have appeared. We though it was due to a cracked lead valley but we’ve had that replaced and the problem is continuing. Using a dehumidifier in the room seems to dry the wet patch and the humidity levels in the room return to around 50%. Today is was more widespread and I was aware that it was quite windy last night blowing into that side of the house (we can hear a hopper on a downpipe below the room with the problem when the wind blows in that direction). I’m not aware it was raining much yesterday/last night. The patches tend to appear overnight....heating and dehumidifier are off and my teenage son is in there.  We have had quite a lot of condensation on the window in that room in recent months, suggesting some dampness somewhere. We have been in the loft above and there is no evidence of dampness anywhere there. The insulation above is dry. I’ve included a photo above. The roofer who replaced the lead flashing valley said everything was good on the roof although some pointing around the ridge tiles in a different part of the house needs replacing although it isn’t causing a problem. There’s no evidence that could be causing the problem.  We’re at a loss.. any expert advice would be welcomed! 

greatcrested

Blocked or leaking gutter, or misalighned gutter.

Blocked or leaking downpipe from the gutter, or problem with the hopper overflowing.

Problem where the roof tiles overhang the wall above the fascia, or fascia problem.

Rotten / torn roof felt beneath the tiles. When wind blows hard rain blown under the tiles and not captured by felt.

Atomix

Maybe use a pad saw and cut a small piece out / take a look? (Looks like the plaster will need replacing anyhow)
otherwise your just guessing...

davilown

Is it on a southwest facing wall? Could be driving rain?

3figures

davilown said:

Is it on a southwest facing wall? Could be driving rain?

No, it’s an east facing wall. 

davidmcn

3figures said:

davilown said:

Is it on a southwest facing wall? Could be driving rain?

No, it’s an east facing wall. 

Nevertheless it could be rain penetrating the wall - does it look like it might need repointing? 

3figures

greatcrested said:

Blocked or leaking gutter, or misalighned gutter.

Blocked or leaking downpipe from the gutter, or problem with the hopper overflowing.

Problem where the roof tiles overhang the wall above the fascia, or fascia problem.

Rotten / torn roof felt beneath the tiles. When wind blows hard rain blown under the tiles and not captured by felt.

We wondered about guttering although no obvious signs of them being blocked or overflowing which seems odd it it’s that. Someone is coming today to have a look at that today. It did seem worse on the morning after it had been windy. It was also bad when it had snowed.

3figures

Atomix said:

Maybe use a pad saw and cut a small piece out / take a look? (Looks like the plaster will need replacing anyhow)
otherwise your just guessing...

We’re hoping the plaster won’t need replacing once we find the source, just decorating, so reluctant to cut a piece out until we really have to. 

3figures

davidmcn said:

3figures said:

davilown said:

Is it on a southwest facing wall? Could be driving rain?

No, it’s an east facing wall. 

Nevertheless it could be rain penetrating the wall - does it look like it might need repointing? 

Yes. We thought that was a possibility. The wall is rendered and looks fine at least to the inexperienced eye. 🤷‍♀️

greatcrested

If rain gets into cracks in render, it cannot escape/evaporate when the sun comes out, so penetrates the wall.

Bets time to check gutters etc is to stand outside in heavy rain and see what happens!

3figures

Having having inspected the loft again and pulled back the insulation, is this gap above the airbrick under the eaves likely to be a problem? It’s not visible from outside (although the airbrick is) but it’s very close to the site of the initial wet patch. There is no evidence of wet patches in the loft though. Other wet patches appeared elsewhere but this seems to be near the first place it always comes in.