Help! Damp patch - how to get rid of it?

[Excellentstick]

We have a damp patch which a appeared on a wall in our entrance hall.

First noticed it about a year ago after moving back in after having an extension done. The patch was pretty small at the time and we were told it was condensation (moisture levels in the house were really high due to the build) and that normal living in the house would mean it would dry out. it's just above the skirting board and around a plug socket. It's also an internal wall - it's right next to the stairs, there's a tiny bit of wall which runs horizontally from the stairs and then the lounge door is perpendicular to this.

Over the past year we have ensured that we've kept our house ventilated by opening windows, we don't dry clothes in the house and we're regularly going in and out of the front door in the tiny entrance hall, further ventilating the area, but the patch is getting bigger (I'd say it has grown a further 2-3 inches up the wall). The floor of the hall is tiled with small red clay tiles, under that are older small red clay tiles and then a concrete floor. On the other side of the wall is just dead space under the stairs which we cannot access as we have no under stairs storage - ours are just all blocked in.

We also have a few damp patches in the house which were also attributed to condensation and appeared after the build. This particular area is bothering me the most at the moment because it's in such an obvious place and in an area of high ventilation - I thought this one would be the first to dry out. Any advice?

Bump

Hi Op, I can't help but Piglet John seems to be the go to guy for these kind of questions. Hope he checks in soon 😀

We had the same (down to the red tiles!) in our first home which was about 90 years old. Our neighbour (semi detached same house!) said it was condensation from the tiles?iirc ! Anyway we had the walls replastered and repainted and it never appeared again! Not sure if that helps!

Oh I just remembered the rest of the downstairs had the original plaster stripped away at the bottom of the walls which we discovered when we took the wall paper off and there was some sort of concrete looking stuff there- about 10cm up? None of the walls with this had any damp.
The damp on that wall may also have gone because we used the central heating and I'm a demon for opening windows. The previous occupNts weren't!

Is it a 1930's house?

Have you got a water meter?

If you drew a line from where the outside stopcock used to be when the house was built, to where the kitchen sink was when the house was built, would it pass this damp patch?

Thanks for the replies.

Yes it's 1930s (ex council rather than bay windows etc) - for the line to pass the damp patch that would mean the stop cock would be outside the front door, would that have been likely?

And yes it has a water meter

mine was 1930s, interesting asking about where the sink would have been.. would it not have been where the kitchen is now? ours was a galley kitchen on the side of the house. but had two odd rooms downstairs that i never. ould figure out what their purpose was! we had one plumbed up as a utility and the other plumbed to have a downstairs loo.

one of these would have followed the same line as the random damp wall.
i wish i had had mumsnet back then to ask!

I suspect the old water pipe is leaking.

Get a teaspoon, a ladle, a rag, a torch, and a doormat.

Turn off all taps and appliances in the house.
Lie on the mat next to the hatch for the water meter.
Pry the lid up with the handle of the teaspoon
Bale out the rainwater with the ladle
rub the glass window of the meter with the rag to clean it.
Look into the window with the torch.
There is a bubble. Is it turning?
If so water is passing through the meter (you can ask someone to turn on a tap so you see the difference). This is much more precise than looking at the numbers on the meter.
Do not leave the hatch open or someone will fall down it and sue you for a million pounds.
r
yn

Thank you. I've just discovered another damp patch in another room that has appeared out of nowhere too. We clearly have a damp issue in this house. Fantastic.

Maybe your building work damaged or disrupted a pipe? We ended up with a massive damp patch from a stupid drain valve on the central heating which had been left slightly open. Tiny leak. Huge damp patch by the time we realised. New block work does take time to dry out, but old walls should be fine still. Is there no way at all you can get behind that wall to investigate? Or under the floor somewhere else?