Sudden appearance of damp on an internal wall

[redhat]

Our house was built in the 1950s and was extended in the 1980s. As a result the living room wall, which was previously an external wall, had an opening cut into it and the room was doubled in size. Two "pillars" remain where the old external wall used to be (and these pillars are presumably holding up a steel joist). They're not actual pillars since one side is connected to the side walls of the room IYSWIM.

We moved into the house six years ago and have never seen any signs of damp. The room was decorated a year and a half ago and the carpet was taken up and replaced with laminate flooring. The skirting boards were replaced and the walls were painted.

Two weeks ago DH said that he'd noticed damp on the skirting board on one of the pillars. He wiped it off before I'd seen it.

I've just noticed a large amount of black mould back on the skirting board plus some white furry mould in an indentation in the skirting board. There is a damp looking patch on the painted wall.

Can rising damp just appear like this after all these years of no problems? It seems very odd. The room is well used and connected to the kitchen and so it is warm. I'm praying that it can't be damp since it wasn't cheap to have the room redone and I really don't want them having to take up floors etc.

The floor to the room is concrete, not floorboards.

Any thoughts?

[CointreauVersial]

First thought would be a leak of some sort. Water can travel under the floor, along pipes, and pop up a fair distance away from the leak.

Any pipes nearby?

[Asprilla11]

Any heating pipes running along the floor or walls anywhere? What room is above it and does that have any heating pipes underneath the floorboards, i.e. could damp be running down the pillar from above (inside the brickwork)?

[redhat]

No pipes in that area of the room as far as I am aware. DS1's bedroom is above so no water there apart form possible heating pipes. The room to the left of this one is a downstairs toilet but I haven't been aware of any problems there. I should maybe investigate that and might also put the heating on tomorrow morning to see if I can trace where the heating pipes go. I wonder whether there is a leak somewhere.

Argh, I feel like its always two steps forward and three steps backwards with this place!

[jollyjester]

Call your insurance company and get a leak detection person out.

My parents noticed a small mould patch on a wall last year and it was a leak in a pipe about 3 metres away. Not to scare you but they had to get a lot of work done.

[Asprilla11]

You definitely need to rule out heating pipes or water supply to toilet or sink first. If you can access the floorboards fairly easily then try and do this yourself. Because these pipes are under floorboards or even buried inside walls in older houses it can be difficult to spot.

If you can't manage to do that yourself, then perhaps a tradesmen you know or family friend. Failing that, as mentioned above you could speak to your home insurance.

[redhat]

Right I'll get the heating on tomorrow and try to work out where the heating pipes are.

[Idontknowwhoiam]

I suspect it may be because you've had laminate flooring laid and the carpet isn't there to absorb excess moisture.
A leak detection will usually incur your excess and many insurance companies won't do it with more than a bit of mould as evidence.
If the mould can be wiped off and doesn't seem to be coming through, in my experience it's poor ventilation and/or excess moisture and a dehumidifier would be most use.

[redhat]

I'd have though that it's unlikely to be poor ventilation. We live in the middle of nowhere and I work from home. I have all the doors and windows open all day every day unless it's really freezing.

Could be connected to the laminate flooring (although that has been down for more than year and a half now and this mould is very recent).

[Idontknowwhoiam]

If you've got a concrete floor and it's next to the kitchen there is a vast difference in temperature and condensation can form then.
Is the mould ina cold par of the room?
Again, the main sign that it's coming through (ie from pipes) rather than surface would be the wall or skirting being damaged.
Is the wall or wood soft? If not and it's purely wipeable damp it's highly likely condensation rather than anything more sinister.

[Idontknowwhoiam]

Excuse my one handed spelling errors!

[Asprilla11]

If the wall isn't attachd to next door, is there anything on the outside of that wall, guttering above or downpipes, a gulley? Check the damp course.

Idontknowwhoiam Makes a good point about the laminate fllor, even if it's been down 18 months the change of weather maybe starting to affect it. Was enough gap left around the flooring to allow it to expand? What was put under the laminate prior to it being laid, was the concrete floor in good condition, no signs of damp?

Lots of things to check and probably seems never ending but there could well be a simple fix so don't get too downhearted.

[redhat]

Well that could be good. I can cope with it being condensation. The room isn't cold at all though, its only 4m by 4m and there are french doors to the kitchen which are open all the time and so its really like an extension to the kitchen. If anything, it sometimes gets too hot in there when the DC are watching a film, or playing on the pS4 with the doors shut.

The pillars would once have been an external wall but they're not anymore. The plaster isn't soft and the skirting isn't damaged. The mould was both black (along the top of the skirting board) and also white and fluffy like candy floss on the face of the board.

I'll grasp that beacon of condensation hope though until the morning....

[redhat]

Actually, I wonder whether the fact that we have the external doors open even when its raining so much could have increased the humidity in the house? We have a large glass roofed terrace and when its warm I sit out there a lot working even when its raining. The doors to the house are always wide open.

[wowfudge]

So the pillars are where the extension is joined onto the original house? Is there flashing on the external side of that wall where it joins into the extension? It any of it loose? Rain could have penetrated if it is and in warm conditions the mould has bloomed, especially if the moisture is trapped by the flooring.

[redhat]

The "pillars" are less pillars really and more sticking out bits of wall where the old room used to end. They support the RSJ which is now midway across the room (so they sort of form a square archway) across the middle of the room.

Im not describing it very well. The room used to be about 2 metres in depth and 4 metres wide. At some point in the 80s it was pushed out so that a mother 2metres in depth was added. They knocked out the back wall, but so that an rsj could be put in, two little bits of the old back wall (about 30cm in width) remain, one on each side of the room.

The "pillar" in question therefore used to have an external face (its back) but now doesn't have any external faces IYSWIM because of the extra 2 metres of room.

If it makes a difference the house is also rendered. The render is in decent condition and has recently been re- painted.

[dotnet]

Some people have said there may be a leak from a buried pipe. You could buy a pipe detector (probably ebay will sell them)- then, if nothing shows, you've at least saved yourself one callout fee.

[dotnet]

ps: Damp proofers usually issue LONG guarantees. Mine is for thirty years. You could call your damp proofer back.

[redhat]

That would be good but the damp proofing/extension was done long before our time (and also before the previous owners' time). I have no idea who did it.

[PigletJohn]

I's a leak.

Have you got a water meter?

They're called Piers.

[redhat]

I thought our water was metered PigletJohn but I'm not sure where the meter is. I haven't seen one in the house. Maybe out by the roadside or would that be weird?

Piers! That makes more sense than pillars.

[PigletJohn]

look for a six-inch square trap, iron or black plastic, in the pavement. Take an old teaspoon to lever it up, and a torch, and a ladle to scoop the rainwater out, and a rag to get the dirt off the glass window. You might want rubber gloves. There may be ants. In the middle of the window is a bubble, which spins when water is moving. Does yours stop when all taps are off?

[Ruhrpott]

I think Pigletjohn always recommends sticking some cling film to the wall where there is damp. If the water collects on the inside towards the wall it is from the wall and if it collects in the surface it's condensation.

[Ruhrpott]

Oops should maybe read whole thread before posting see that Pigletjohn has already posted

[CointreauVersial]

I thought for a moment that PigletJohn was saying all water meters were called Piers. Bit of a posh name, I thought, and how does he know?....

I know exactly what layout you're describing, OP, because we have exactly the same here. Piers!

[FoxyLoxy123]

I had two patches of these. One down to leaky rad pipes and the other down to a leaky washing machine pipe that was supposed to have been fixed before we bought it. The latter was worse because the concrete floor meant the leak didn't drain away quick hence spread up the walls. Got lots of yellow patches now.