Condensation or damp?

[keeley1]

Hi!

I’ve been reading the forum all morning trying to figure our problem out but thought it may be easier to post for advice from anyone who has more knowledge than us!

We live in a 1930’s detached house. We moved in in January and stripped all the walls in the living room back to brick, bricked up the old fire place and added an air brick and replastered and decorated. The walls are solid brick with no insulation. It’s worth noting that when it was back to brick, there were no signs of wet or damp anywhere.

Maybe about 2 months ago when the weather got cooler we noticed a damp looking patch in the corner of the room. It didn’t feel wet, just cold and doesn’t smell damp. We have a dehumidifier so put that facing the corner and it went away. However it does keep coming back, not too often but obviously would prefer to nip it in the bud whilst it’s not a big issue (hopefully).

We run the dehumidifier quite often and try to keep the house at around 55%. The heating is set to 19 degrees.

I’ve checked the other corner of the room and there is a tiny patch there too. Does this look like cold patches / condensation or something bigger? My fiancé is currently taking up the floorboards in the undecorated hall to crawl in to the floor space to check down there.

I’ve attached two photos. Any advice would be greatly appreciated! Thank you!

 

[Wayners]

Buy a cheap damp meter

 

[^woody^]

Buy a cheap damp meter

Yes and you'll find you have damp everywhere even in the ceilings.

 

[^woody^]

Black/ brown stains in corners is invariably mould from condensation. You have the classic crescent pattern there.

There may be underlining causes, but a very cold corner and higher interval humidity are factors to be investigated.

 

[JohnD]

is the floor concrete or wooden?

What is on the other side of the two walls?

Does anybody drape wet washing inside the house?

The damp patch round the aerial cable is probably rainwater running down it. Does it pass through a hole in the wall? Photograph the other side please and I will explain Drip Loops.

 

[keeley1]

Black/ brown stains in corners is invariably mould from condensation. You have the classic crescent pattern there.

There may be underlining causes, but a very cold corner and higher interval humidity are factors to be investigated.

thank you for the reply

 

[keeley1]

is the floor concrete or wooden?

What is on the other side of the two walls?

Does anybody drape wet washing inside the house?

The damp patch round the aerial cable is probably rainwater running down it. Does it pass through a hole in the wall? Photograph the other side please and I will explain Drip Loops.

thanks for replying!

It is the front exterior wall. The other side of the larger patch is:

we’re both wondering whether the air brick has anything to do with that section as it’s almost directly above/behind that. My fiancé tried to get under the floor space but there’s some gas pipes in the hallway section that’s already cut and we don’t have a circular saw to cut a new hole in the dining room.

the other side of the small patch with the cable is:

The cap Virgin put over it has come loose so that could be that?

Flooring is wooden and vaulted. We do sometimes dry clothes indoors now it’s wetter but our dehumidifier is also a clothes drier, we usually do it in the back of the house in the utility room with the door shut and dehumidifier on. No clothes are ever put in the living room.

 

[JohnD]

The replacement plastic window might be a source of damp. Is there a damp patch below it? There is a part of the wall that seems to have a horizontal crack. Stand back and show more of the wall. It might be possible to see shading of the bricks if they are damp. I think you have cavity walls, not solid, but this wil be clearer when you stand back and take a wider pic.

The bricks around the Virgin box appear to be damp and efflorescence is showing indicating long term damp, either from a leak or from groundwater. The airbrick at that point has a damp look to it. Photograph the whole wall up to the roof so we can see the gutter and downpipes. Does the damp get worse at periods of persistent rain?

If water is able to drip into the cavity from the window, it can appear low down on the inside leaf, and it could also drip onto the TV cable.

Pour some water on the ground beside the house, and see if it runs towards the house, or away. If water can run in through the airbrick that can be a bad source of water under the floor.

One of your airbricks appears to be clogged, and I can see the ground level around it has been raised above the ground level when the house was built. Judging by the fat mortar joint, the DPC runs at the level on top of the aitbricks.

It is very common for idiots to raise the ground level beside a house and create damp when laying new paving. This can be cured by digging a small trench beside the wall, so that water cannot rise up and the brick is exposed so it can lose water by evaporation. Water can also drain or run away at the bottom of the trench. You can fill the trench with pebbles or cobbles, but not with small stones or gravel (small stones permit water to rise by capillarity).

 

[Jayd S]

Agree with JohnD about height of path outside being too high and possibly causing damp/colder walls inside. Also, could be gypsum plaster instead lime plaster which allow walls to breathe and, therefore, dry out. Check out some of Peter Ward's vids on YouTube about older houses - very informative

 

[keeley1]

Thank you both for your reply’s.

Really informative and much appreciated. I will get a photo and try the pouring some water tomorrow and will let you know

 

[^woody^]

The inside image slows a corner and the cable entering the wall.

The external images show different places but not where the cable should be exiting.

What's the correlation?

 

[keeley1]

The inside image slows a corner and the cable entering the wall.

The external images show different places but not where the cable should be exiting.

What's the correlation?

sorry, that’s my mistake. My fiancé’s reminded me that the cable is actually exiting straight out the wall through the Virgin box. The internal cable is excess which has been plastered in to the wall to hide the cabling. Hope that makes sense.

 

[^woody^]

sorry, that’s my mistake. My fiancé’s reminded me that the cable is actually exiting straight out the wall through the Virgin box. The internal cable is excess which has been plastered in to the wall to hide the cabling. Hope that makes sense.

But where is that cable exiting on the external pictures? There is no corner shown on the external photos and the external boxes don't tally with that internal box.

 

[keeley1]

But where is that cable exiting on the external pictures? There is no corner shown on the external photos and the external boxes don't tally with that internal box.

it’s behind the second two photos. The brown cap on the outside is covering the cable.

 

[^woody^]

Really? That's 300mm above the DPC