Damp/rot

[OrlandaFuriosa]

Stretching its fingers over my chimney breast like a vine. Advice?

If you own the house, get the flashing around the chimney checked, as this is most likely to be the cause.

A picture would be helpful. It could be dry rot (try googling it)

Dry rot only affects timber?! Might be salt damp. blog.completepreservation.co.uk/2014/06/02/the-damp-stains-on-the-chimney-breast-is-it-salt-damp-or-a-leak/

It can grow on brick work - it does not confine itself to timber.

Gosh, didn't know that! Hope not dry rot OP.

Thanks for all of this.

I’m not sure if the attached photo will come out. It’s a very faint grey creeping tendrilly pattern .

Trying again, having played with contrasts etc. Still not v good.

I think that's water damage tbh - it's just the way it's coming through. Is the fireplace open or blocked up? If it's boarded over, is there a ventilation grille?

Thank you, and I’m impressed by your eyesight. It is open and we use it, though I fear magpies may have nested in it.

What I’m perplexed about is that, say 5 weeks ago it was a small area, my family told me in no uncertain terms it was dirty handmarks. I left it and it has spread, in this dry weather.

Does it come and go depending on humidity? We've got a couple of damp patches next to our chimney breast, various people who've been out to look have various theories, and we think it might be salts (mentioned upthread). The patches fade away in low humidity/get worse in high humidity.

Hmm - do you know when it was plastered? Have you had no rain at all? If you've had some rain, what's it like after that, any changes? I'm now wondering if it's something else, rather than water (so much for my insight). If it's salts then they will eventually come to the surface and it will look blistered and powdery. Has it always been a house or is it a conversion?

Soot isn't just dirty, it's greasy too. With the moisture in the chimney dried up, it could be that coming through the brick or stone work There was an episode of Location, Location, Location where an outbuilding was a converted animal shed and there were splodges on the plaster where the dabs of the dot and dab were. A local surveyor said it was the really old animal gunk (technical term) in the walls being drawn out through the dabs. Something to do with everything drying out as it was now a watertight building.

You could try a stain stop paint over the area then repaint to seal it in so it doesn't show through.

Plastered before our time, so at least 28 years ago.

It’s got worse in this period of dry weather. Doesn’t look like salts coming through, I’m used to that.

My builder hasn’t rung me back so I need to find another, I suspect, but everyone is on holiday and I normally want to know roughly the problem before I engage with that profession.

It’s always been a semi detached house. This is the chimney on the party wall.

Ask next door if they've noticed anything on their side - and watch their faces in case they've done something which might be connected!

Will do. They’ve insulated under their floor ( we have a void underneath) as well as putting a wood floor on top and I know our cupboard under the stairs has got damper, but of course they can’t tell.

Equally I recarpeted recently and that might be the cause.

I think it's old cracks in the plaster showing through the decoration. It's common in older houses. If it's only on the chimneybreast it might be heat-related. Rot tendrils don't show like that, unless you've just pulled off cladding or something and they've been growing out of sight.

If you want to see if the wall is damp, tape a piece of clear plastic tightly to it. If the wall side of the plastic mists up and gets water droplets, the wall is damp.

If the room side gets water, the air in the room is damp and causing condensation.

BTW your other description suggests your neighbours might have blocked the airbricks or circulation under their floor. Some people actually do that deliberately... When you take up a floor to insulate, that's the time you should clear out airbricks and ensure good airflow.

Once again, thank you. Clear plastic it is. I suppose with this dry weather and modern plaster, as opposed to the old lime versions, it might show more.

I wouldn’t be at all surprised about the ventilation bricks.