Help! Damp!

[InsolentAnnie]

We have a 1930s house with a modern extension. Damp has appeared over the past year: mould in the corner above the skirting boards (goes up a foot or two), and a dark patch that goes across the wall to the chimney breast - the slate hearth looks slightly darker on one side too. In the other front room there’s a damp patch on the chimney breast (which doesn’t have a fireplace or air brick) which gets worse when it rains, and a couple of other darker patches on internal walls which are behind furniture.

My thoughts are rising damp in the first room (or bridging of the damp proof course), and penetrating damp due to no ventilation of chimney breast in the second room - not sure about the other patches in that room, maybe condensation? We do have a DPC that the previous owners had injected but maybe it’s been bridged.

So - who on earth do I get to look at this? Do I pay for a specialist damp company to do a survey, and not have a clue whether they are being truthful about the amount that needs doing? Or do I get some sort of other independent surveyor in? I don’t know who to call! Any advice much appreciated - thank you!

Should have said both rooms are in the original bit of the house!

You can find a damp company to investigate for you, but better not to go for ones who offer free survey, nothing is free.
Be aware that damp companies will always try to sell you damp proof courses which may not solve the problem. What you want to do is to find out where water is coming in and how to stop that happening.
Is your chimney/roof in a good condition? I had damp meter readings on my chimney breasts, but no damp patches. Just had a roofer cap my chimney pots and filled the missing concrete, will add vents on the chimney breast soon, hope that will solve the problem.

Agree with pp you need a damp company to check the problem but don't sign up for any expensive work.
My damp was caused by the chimney, there's a chimney on the roof but the chimney breast had been removed in the house, the water getting in from the chimney was leaking into the walls and appearing as damp in different areas.
It was fixed by roofer who sealed the chimney to stop any further water getting in £250, then a builder chipped off the damaged plaster, put a waterproof sealant?? on the bare walls and rescimmed the walls £500, best money I've ever spent, no more damp.
Definitely get a company in to do a damp test though

Don't get a damp company as they'll just sell you damp products. Get an independent surveyor who is familiar with damp and identify the cause first.

Independent damp surveyor with no links to any damp company.

Or wait for @Pigletjohn to come on this thread with some advice.

post some photos please.

the inside wall, all the way from floor to ceiling including any current or former chimneybreasts, radiator pipes, and the floor under the carpet (is it concree beneath)

and the other side of that wall, all the way up the gutter, and down to the ground, includsing any drains, pipes, manhole covers, paving, taps, airbricks, wild tomato plants

tks

Thanks @PigletJohn Can’t fit whole wall in photo…! Green wall is the one where the chimney is used (log burner). Interestingly the damp and mould only appeared after I touched up the paint. We had both rooms reskimmed a few years ago with normal plaster - original walls are lime plaster. I did wonder if adding another layer of vinyl paint didn’t help either.

Blue room started off with just the biggest patch (on the chimney breast) that disappeared a couple of times over the summer. Seems to be worse when it rains and has now spread. Other photos are new patches on the wall that separates that room from the hall (so an internal wall).

I can’t get the carpet up in the green room to have a look! Floor is parquet underneath, like the blue room. It was dry when the carpet was laid a year ago, which was after the damp patch appeared. The entire roof was replaced a few months ago and both chimneys repointed and flashing replaced. Blue room chimney is capped. I’ll get more external photos when it’s light!

You can see on the previous photos that the mould extends almost to the picture rail. Here’s the rest of that damp patch, plus an external photo (no drains behind the gate, they’re all on the other side of the house - I’ll get a photo of the other side of the chimney breast tomorrow) and close up of the skirting board. It’s always been discoloured, before any damp showed.

Blue room chimney breast and better shot of the corner just to the right of it

Wall opposite chimney breast - all internal walls (hall is the other side)

We had both rooms reskimmed a few years ago with normal plaster - original walls are lime plaster.

Not saying this is only problem, but this is definitely a problem that will cause damp walls. You should never ever cover over lime plaster with regular plaster in an old home.

Other than that, the placement of the damp on chimney breasts and such does indicate you also have water leaking in from somewhere above...guttering, downspout seams, etc. I know you said roof was redone/chimney capped, but it may not have been redone correctly. PigletJohn will be able to say once you have posted external photos.

@PlanDeRaccordement Yes I’ve since found that out - had never had an older house before so we didn’t know. Now kicking myself for not insisting on lime plaster! DD’s room (which is above the green one) had yellow furry stuff all over the wall. There was a crack in the render which we repaired, and I think that’s where the wall was getting damp, but I stripped off the wallpaper so now can’t tell if it’s come back because the wall underneath (lime plaster still - thankfully we hadn’t done any of the upstairs rooms) is so many different colours..!

The house doesn’t smell damp at all, which is one good thing I suppose… A handyman we use often suggested that tanking slurry might solve the damp. Not sure which way to jump!

I really need you to stand back and take a wider pic to put the damp into context

from what I can see the damp is in an internal corner, and looks to me like a leak, either plumbing, or roof or chimney.

chimney leaks usually leave brown or yellow stains from the tar and soot, unless the chimney has never been used and is clean. Old wood can also leave brown stains, but does not smell tarry.

So from what I can see you do not have so-called rising damp. It is too high and too narrow to be coming from below. And it is not condensation. It is running down from above.

Is there a bathroom above?

Photograph the chimney when it's light.

p.s.

tanking slurry does not cure damp.

It hides it.

@PigletJohn Thanks. Re: tanking slurry, that’s what I was afraid of and why we haven’t done it yet as I wanted a second opinion. Nope, only bedrooms above both rooms. I’ve never noticed any coloured stains - when the big one in the blue room dries up a bit it doesn’t really leave any mark.

Will take a full photo of both walls in the light tomorrow, along with the external shots. Thanks so much!

p.p.s.

try and work out if the floor is concrete. A wooden floor with a void underneath will not feel so hard when you jump on it, and will have airbricks showing outside to ventilate the wall. Look at the floors in adjacent rooms, and jump on them. Is the parquet swelling or lifting?

If water is running down and soaking into a concrete floor, it can wet the walls, especially if they have been plastered all the way down to the floor with no gap behind the skirting.

have you got a water meter? What colour is your hot-water cylinder? Does your boiler have a pressure gauge?

@PigletJohn Finally managed to get photos in the light!

We have a water metre, no hot water cylinder, boiler with pressure gauge (pressure currently fine).

Here’s the full blue room wall and external shot. Excuse the half-painted house!

Blue room…

External wall

Internal wall (other side is the hall). There’s another patch the other side of the door above the skirting board, which is behind a desk.

Top of that side of the house

Top of that side of house

Green room (other side of house) - mould is in corner but darker patch goes right across under the window to the chimney breast

External shot of that chimney breast (can’t get any further back!)

In the grey room, it looks like there is a wet streak in the corner going right up to the picture rail. Or is it a shadow?

Walk round the outside hitting the render. Does any of it sound hollow or fall off?