Upstairs chimney breast damp/staining?

[ginberry4]

Chimney breast in DS’s room has many damp patches / staining which are not wet to the touch but certainly look it.
The fireplace/chimney had been blocked downstairs with no ventilation for a number of years, this has now been fully opened and swept (it was also heavily birds nested). It is also ventilated in DS’ room. The chimney stack has a vented cowl on it which the chimney sweep said is the correct fitting to allow airflow and prevent rainwater getting in. We’ve had the pointing inspected on the chimney stack & external wall & this is due to be repointed in the next few weeks.

There is no guttering or pipework on that side of the house so no other place water can be getting in. I think we’ve done everything we can to resolve the problem externally - so now just want to know how we can get rid of these patches internally. If anyone has any suggestions it’d be much appreciated. Thanks

Just to add - this is an upstairs room

are they new stains?

if you poke a wire through the airbrick, does it find a mound of builders rubble?

is there a detectable current of air through the airbrick?

Do you drape wet washing in that room, or have a nearby bathroom or shower?

Does the radiator leak?

Has the flashing around the chimney been redone?

Forgot I’d posted this!

No not new stains
No builders rubble through air brick. Its not actually a proper air brick - we drilled a series of holes through in an attempt to ventilate it before the downstairs was unblocked. We had it swept 2 weeks ago. There was lots of birds nest up there but now it’s completely clear.
Yes there is good airflow through the airbrick/holes. We have a completely open glue downstairs too.

No washing draped anywhere upstairs. Only done occasionally downstairs in conservatory.

Bathroom nearby but not adjoining - just used for baths.

Radiator does not leak.

Flashing on chimney stack was redone when we bought the house. Roofer has checked it & says it’s ok. Just the repointing to do but he said in his view it wasn’t that bad. We have 2 other chimneys, one in use, one not (ventilated) and neither have this issue.

www.toolstation.com/zinsser-cover-stain-primer-paint/p56164?store=G2&utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&gclid=CjwKCAjwh7H7BRBBEiwAPXjadiH9MI6PcHFc6-cEbArw_W5Tev89IrnkZ7ahePD7LSG4FyKm5C1mvxoClSkQAvD_BwE

Should say open flue not glue! Stupid autocorrect!

you mention sweeeping and birdsnests.

Each fireplace has its own flue.

So do you mean the downstairs fireplacer flue was swept, but not the upstairs one (which seems to be bricked up)?

Stain-concealing paints will not remove damp.

Hygroscopic salts.

@PigletJohn

you mention sweeeping and birdsnests.

Each fireplace has its own flue.

So do you mean the downstairs fireplacer flue was swept, but not the upstairs one (which seems to be bricked up)?

Stain-concealing paints will not remove damp.

The chimney breast in my photo is literally just the flue (is that the right word? Chimney?) for the downstairs fireplace which passes through DS bedroom. It is not a bricked up or separate fireplace/flue in its own right, if that makes sense.

@MillStone

Hygroscopic salts.

No obvious sign of salt on the walls - would it be visible to the eye? We have some damp/salts downstairs which has damaged the plaster but it looks very different to this.

How do I prevent it coming through in an upstairs room? I’m wary of using damp seal paint - we did that once before & the damp just found its way around the area we painted!

it wil be interesting to see where it is coming from.

tape a piece of clear plastic tightly to the wall. If the water is coming through the wall, you will see mist and beads of water forming on the plastic against the wall, an the plaster getting increasingly wet. Damp that is coming from inside a flue usually causes yellow or brown stains.

If it is condensation, you will see water forming on the outward, room side.

Have you looked in the loft for tanks or pipes?

There’s no tanks/pipes in the loft. We had a Combi boiler installed & tank & all pipes removed from loft a number of years ago, when we had a loft conversion done. The wall has done this for a number of years, at certain times of year it looks worse than others.

I will try the plastic & see what happens. There’s no yellow or brown staining at present nor are there any visible droplets of water or salt.

It may be it has been coming through the pointing or that the birds nesting was bridging it. Am hoping with all the work done that will resolve it, it’s just how to then get rid of these patches. Could a dehumidifier do it?

if the chimney is properly ventilated, then there are not many potential sources of water.

Rain, leaks, condensation

The pattern does not look to me like hydroscopic salts, it looks like damp from the brickwork, such as a rainwater leak above, such as poor flashing or benching. I have also seen similar from a severe burst pipe above.

Photos of the roof and chimney would be interesting, and any signs of damp external bricks. What colour is the flashing?

Can I ask what you mean by benching? I’ll try & take some pics of the roof/chimney tomorrow. The roof (slate) was also replaced when the loft was converted & these damp patches pre-date that.

Roofer said it all looked ok but I will ask him to give it all another thorough check when he does the repointing.

I should have said flaunching.

Benching is in drains. Mental block.

Hi @ginberry4 did you ever get to the bottom of this? I have a very similar looking issue on upstairs chimney breast and tearing my hair out (whilst bankrupting myself!) trying to figure out what's causing it.

@ginberry4 any better? We also have this on chimney breast, just paid for a new roof to fix it and the damp is still there. No chimney left as it's been taken down. So frustrating.

We're going to try painting the outside wall on other side with damp seal paint. Would that work?

Show us some pics.

@PigletJohn mine looks like this..thought cause was cracked render initially, that has now been replaced. Wall is very cold but when it rains it feels wet to the touch. Roof has been looked at and some bits repaired as well, been in the loft above when it rains heavily and it is bone dry up there. Now thinking it is condensation on a cold wall. Have since vented the chimney breast top and bottom externally and internally at the bottom. The chimney has been taken down below roof level prior to purchasing the property. Any advice much appreciated, my next step is to try and decorate over with stain blocker , keep using the dehumidifier and if that doesn't help board over in the spring.

I think it looks like wet wall. But to find out, tape a large square of clingfilm tightly to the wall, and watch to see if water forms on the wall under the film, or if it forms on the room side of the film, leaving the wall dry (which is condensation).

We've been scratching our heads with this for 18+ months, had more than 10 roofers through the door to quote for the new roof, joined umteen forums to ask for advice and I finally think you've cracked it @PigletJohn Bloody wet wall
So now we've got a plan at least! Thanks so much 👍

thanks for resurrecting this thread@Iggityziggety @Arewethebadguys - yours does look very similar to ours.

5 years on ours is still like it. Had the wall repointed externally & eliminated everything we could think of but it’s made no difference. I can’t remember if we ever tried @PigletJohn’s suggestion of taping clear plastic to the wall so will do that again. Our only other thought was to strip the wall back to bare brick & check the internal pointing.

@PigletJohn when you refer to it as wet wall, what is the usual cause?

Water coming from somewhere. Often a leak. Depending on position it might be an exterior wall, with water pouring down the outside from a faulty gutter, or a leaking bath above. Or a radiator pipe. More rarely a defect in a wall allowing rain penetration. Or something else.

@ginberry4 I've been advised mine is condensation on a cold wall and since I've been running a dehumidifier I have to say the wall is no longer shining wet when it rains. Also got a hygrometer that shows the humidity in the room (which goes through the roof when it rains) so I can target run the dehumidifier. The long term solution is apparently to board over the wall so that the warm air is no longer hitting a cold surface.

"Also got a hygrometer that shows the humidity in the room (which goes through the roof when it rains)"

What are the numbers?

Is the rain getting in?