Damp on internal wall?

[opps]

I'll try that out. Will also cut back some of the plaster just in case. Cheers all.

I would try the emulsion first before considering hacking away the plaster.

If the emulsion passes the scratch test, just use a stain blocker

 

[Tentontousand]

I think the clue is that it appears to be travelling up the wall corners where the metal strip is, and not horizontally which is what you would expect if it was coming from the ground. Is there a draught/air circulation in this area? get an infrared thermometer and see if this is a cold spot. If it's a few degrees lower than the surroundings, then you have a possible reason/solution.

I have seen similar in our house next to a fridge with a bottom fan. Obviously a humid area because of the fridge defrost mechanism evaporating the melted ice on defrost, and the fan was circulating the moist air past a cold wall nib just like this, which continually caused condensation.

Just to add, we have a large opened up fireplace, the back wall of which is exposed brick and the party wall to next door - 9" thick brick wall. That wall goes down to ground level. Using my own infrared just now, the base of the wall inside the fireplace is fully 2 degrees cooler than the upper area of the back fireplace wall, which illustrates how the wall closest to the ground is a cool spot and losing heat in to the ground, even though it's in the middle of the house. If there is a condensation risk due to the humidity and dew point, a 2 degree cool spot would be more than enough to show up localised condensation.

I wondering if cutting down those metal beads would help in some way... worth a try I guess. No appliances like that near these walls for me though.

 

[Koolpc]

Have you got a dog? Do you take him out for a pee?

 

[mrrusty]

I think if it does show up as a cold spot, I wouldn't hack in to the wall. First I'd try and work out if there is any way to drop the room humidity a little - even just reducing the room temperature a degree or two will reduce the ability of the room air to take up and hold water vapour and will hence reduce the dew point. For example room air at 22 degrees and 60% RH has a dew point of ~14.5 degrees, but room air at 20 degrees and 60% RH has a dew point of ~12 degrees.

Not saying it's definitely condensation, but it isn't very well understood and is far more prevalent than people sometimes realise.

 

[foxhole]

Have you checked loft above this position ?

 

[Tentontousand]

Have you checked loft above this position ?

Nothing in the loft straight above

 

[Tentontousand]

Have you got a dog? Do you take him out for a pee?

No dog, I do have a cat but I think the smell of a cat urinating on my wall would stink! No smell though

 

[Tentontousand]

I think if it does show up as a cold spot, I wouldn't hack in to the wall. First I'd try and work out if there is any way to drop the room humidity a little - even just reducing the room temperature a degree or two will reduce the ability of the room air to take up and hold water vapour and will hence reduce the dew point. For example room air at 22 degrees and 60% RH has a dew point of ~14.5 degrees, but room air at 20 degrees and 60% RH has a dew point of ~12 degrees.

Not saying it's definitely condensation, but it isn't very well understood and is far more prevalent than people sometimes realise.

Humidity on our dehumidifier is showing roughly 55 in the area which I believe should be an okay reading

 

[JohnD]

How can you rule out a leak under the floor?

 

[Tentontousand]

How can you rule out a leak under the floor?

From pipes? Because we have no pipes under the floor

 

[JohnD]

You already know where the water supply, drains and others pipes used to be when the house was built?

a Victorian home

 

[mrrusty]

is showing roughly 55 in the area which I believe should be an okay reading

Yes. It'll be interesting to see what happens if you can maintain that for a while.

 

[Tentontousand]

You already know where the water supply, drains and others pipes used to be when the house was built?

You talking about old pipes that aren't in use any more?

Water supply comes in from our kitchen and we use to have old CH pipes under the ground but they were made redundant and they all run above ground now. The floor was tested for moisture last year and it passed as dry

 

[Tentontousand]

Yes. It'll be interesting to see what happens if you can maintain that for a while.

We try to keep it maintained around that as much as possible but sometimes it does go over 60

 

[JohnD]

Water supply comes in from our kitchen

You mean from a watermain in an alley behind the houses, rather than from a main under in the road to the front, with a communication pipe passing under the house floor?