Please help with this damp patch on my wall

[JohnD]

draw round the wet patch with a pencil (or chalk - easier to clean off) and photograph it, so you can see if it gets bigger or smaller.

If you put a fan (not a fan heater) blowing against the patch, the moving air will evaporate the water off the surface (you need to ventilate the room to get the water vapour out).

please show some pics

 

[Harry Bloomfield]

Any other ideas, keep them coming

Some sort of fan, to move air around..

 

[dazzler9000]

Cheers all, I will try the fan and chalk ideas also.

 

[dazzler9000]

Bit of an update. I've been in the attic and checked the loft insulation near the eaves and all appears to be dry.

Last night was another cold night and there was a slight damp patch in the morning. We've been keeping the bedroom door open at night to see if that helps. One thing was certain though, there was no rain last night so I really don't think this is water-related.

I didn't point out in my initial post, that the main wall is a solid wall (clay blocks) joining to the gable end which is a cavity wall. I wonder as a precautionary measure if I should just seal the brick with a water sealer?

As I mentioned previously, the wall is very cold inside the room, so I'm wondering if I just need to keep the heating on at night (scary thought with today's gas prices), just to keep the building fabric warm?. Tonight's weather forecasts -2, so I will keep the heating on low and see if this helps.

I've also painted the spare room grey and I had a look in there this morning and that has a very slight damp patch as well in the corner. The damp on the grey is easily spotted due to the matt colour, as it turns dark grey. I looked in my son's room and that was also wet, but it's difficult to see with white paint as it doesn't change colour. I wonder if the problem has always been there (we've only owned the house 2 years), but we've never noticed! What is apparent is that it's probably not just my bedroom!

We do plan to externally insulate our house on the solid walls at some point, so hopefully, this would solve the issue anyway, but that will be some time away as I suspect it'll cost about £20k

 

[Harry Bloomfield]

We do plan to externally insulate our house on the solid walls at some point, so hopefully, this would solve the issue anyway, but that will be some time away as I suspect it'll cost about £20k

I would not expect it to cost that much, those walls are cavity walls, they could do it in a day. They just drill a small hole every yard or so and blow the insulation in. Well worth doing - get a quote for it.

 

[dazzler9000]

I would not expect it to cost that much, those walls are cavity walls, they could do it in a day. They just drill a small hole every yard or so and blow the insulation in. Well worth doing - get a quote for it.

Harry, I meant to add external wall insulation on the solid walls, where they attach foam or celotex and then a couple of coats of render.

I did wonder whether it was worth getting the cavity walls cavity filled as well, but everybody I speak to, says not to, as it CAN cause damp problems.....

 

[dazzler9000]

Just read about 'Stormdry Masonry Water Repellent', which seems to get rave reviews. I wonder if I should just get on with painting the brick with this. Unfortunately, I can't do the white solid wall as it's painted, but I suppose the paint should provide a water seal anyway.

 

[Harry Bloomfield]

Harry, I meant to add external wall insulation on the solid walls, where they attach foam or celotex and then a couple of coats of render.

I did wonder whether it was worth getting the cavity walls cavity filled as well, but everybody I speak to, says not to, as it CAN cause damp problems.....

CAN, but normally doesn't. Mine was done 20+ years ago and no damp here, bills seem to have gone down and it makes the house more comfortable in both colder weather and hotter weather. They did have some complaints, but techniques and materials have improved over the years.

 

[dazzler9000]

CAN, but normally doesn't. Mine was done 20+ years ago and no damp here, bills seem to have gone down and it makes the house more comfortable in both colder weather and hotter weather. They did have some complaints, but techniques and materials have improved over the years.

Yes, I had it in my old house and never had an issue. Nowadays though, all I hear is horror stories.....

If I were to consider it, I'd have to do a load of research. The limited research I've done leads me to believe spray foam could be a more modern and higher performing solution.

https://www.evergreenpoweruk.com/cavity-wall-insulation/

 

[Harry Bloomfield]

Yes, I had it in my old house and never had an issue. Nowadays though, all I hear is horror stories.....

Too be fair, you will always here more horror stories than good outcomes - Those with a good outcome usually have much less interest in any subject.

 

[dazzler9000]

Anybody else got any theories as to what's causing my damp problems?

 

[dazzler9000]

It's been a while since my last post in January. Nearly a year on, I'm still seeing the same issue.

In the summer, I sealed the external cavity brick wall (gable end) with storm dry and it's made no difference, so presumably, this has nothing to do with water ingress through that wall. As discussed previously in the thread, I've had the roof patched also.

I'm convinced this is due to internal cold walls and condensation or (cold bridging). I found this thread which mentions something similar Cold bridges at junctions with existing solid walls

It appears worse, when it's colder and not necessarily been raining. Just to recap, I have a painted solid wall, joining a cavity wall (non-insulated) on the gable end with plaster straight into brick. Our house is very humid although I try my best to limit this, the bedroom is rarely below 75%. I've started to use the dehumidifier a bit more but I'm still looking for answers.....

Does anyone have any experience with cold walls or cold bridging? I'm considering buying a thermal camera, so I can at least look at how cold the walls are in certain areas of the house.

My aim is to externally insulate the solid walls when funds allow, but that could be a few years off now.

 

[JohnD]

.... Our house is very humid although I try my best to limit this, the bedroom is rarely below 75%. ....

Where do you think the water is coming from?

 

[foxhole]

The white soffit board running around the corner , if not sealed will collect lots of condensation overnight and soak the corner wall .

 

[dazzler9000]

Where do you think the water is coming from?

Hi John, was that your way of saying it's definitely water leaking in and has nothing to do with humidity or cold walls?