In the never-ending joy that is home ownership – I’ve not overcome a water-ingress issue when it RAINS (shouty caps for importance of issue). This is preventing me from having an effin’ living room. I feel like I intimately know this issue after 4.5 years…but I’ve not solved it.

It shows itself by a damp patch around the fireplace hearth (adjoined to neighbour’s property) and that wall in general, has damp patches where I’ve dot and dabbed new plasterboard for a foot or so.

So a damp wall, damp hearth on one wall. Just the one.

Only when it rains.

Lifting up the floorboards reveals a fairly damp soil underneath, but not to the point where the soil will ‘clump, but clearly of moisture

I have had:

• Chimney fully repointed, all the flashing replaced, all the old flaunching dug out and replaced and a pepperpot on the one open pot.
• Checked the water mains for signs of leaks. Not a sausage used in 12 hours.
• Emptied the hopepipe down the drain to rear of house in case of a crack. Not a sausage.
• Cried
• Checked airbricks. Now whilst there is a question as to a particular airbrick, but even if there;s an issue there, that doesn’t answer why it’s only when it rains that it becomes apparent.

I live on top of a hill, house is built on old mining site, no streams,no water table issue (as I understand them) etc.

No problems upstairs on the same wall with the chimney in the bedroom.

The issue was here before I installed the driveway, patio etc etc (as when I bought the house I noticed plaster falling off the wall in same place and when I dug out the old hearth , very early on, I had a pool of water when I got to a certain depth).

I’m tempted to just tank the bottom half of the wall and stick something around the hearth so carpet/laminate doesn’t take up water – but that’s not my style and everything on this house has been done properly. I don’t want the next buyer inheriting a bodge.

Help!!

we need pics of out side walls and roof and ground levels etc

you said it is an adjoining wall to neighbour’s property – have you had a proper look from their side?

Stating the bleedin” obvious I know, but you shouldn’t have found a pool of water when you dug out the old hearth. Is it a suspended timber floor or solid?

If your walls are stone (and perhaps even if not) water can seep down internally a long way before making an appearance. The  ingress could be anywhere up to roof level.

The outside of the house has been fully repointed.

The drive levels are in line with being below DPC (or thereabouts) – but the driveway is fully permeable. Now this got me wondering if this was the issue, but it was here long before the drive was installed – previously just masses of concrete. Drive is 18months old

But crucially, the front wall where the drive is (obvs) all the plasterboard is fine.

Same with wall to the rear of the house.

I’m not sure pics of roof will help from ground level. It’s only an issue on this wall, downstairs – all new extruded aluminium guttering, new downpipes etc.

And on the neighbour’s side (she has much sympathy), she said she noticed a very small damp area the other day when she removed some wallpaper, but even then, I’m not sure how having had the whole chimney sorted – even with the notorious bastard that is water tracking everywhere, as issue on her side could make it only onto my floor/wall?

Sorry – engineering brick construction, (1915 ish) with a suspended timber floor. A foot and a half gap in the space with relatively decent airflow. Obviusly the hearth has a brick construction around the outside to ground level too. Plenty of signs of salts in the bricks below (and above floor level for a couple of courses)

Cavity wall construction with that damned foam ball bearing type insulation too (hilarious when the windows were replaced on a windy day 😀 )

But…. it only makes an appearance when it bloody rains!!

Thanks

Cavity trays in chimney….

I’ve googled, but you’re going to have to help me out there!

I’m intrigued because I’m convinced it’s a chimney issue that’s emanating into the wall…but might be wrong.

I’m placing a bet as to chimney on neighbours side then transiting down…

water can travel unseen quite a distance within cavities, as bear says. Not seeing pics of the building my money is on roof/coping/chimney area

The whole chimney has been re-pointed, new flashing and flaunching, including neighbour’s side. Also pepperpots added onto both their pots.

Ok, without pictures I can only relate a similar incident that I encountered on a 1900s property.  It ended up being the old lead flashing having worn through to be porous, but not have obvious holes in.  The water then migrated to the chimney breast and then down to the lowest point.  There was also an issue with porous bricks, but Thompsons Waterseal sorted that along with the new pointing and flashing.

The water that you see will almost certainly be coming down and not coming up by capillary action as it is happening too quickly.

As others have said a few pictures will help.

Iv’e got a similar problem with a terrace house. The dividing wall between chimney and back wall is damp. I looked under the floor and found quite a lot of soil built up against the brickwork. I dug out as much as possible and after enquiring next door its looking like the same thing has happened.

I’m hoping when they clean out there side all will be fine. In the meantime I fitted extra air bricks to try dry it out.

Another option is to drill the bricks and fill with silicone damp proof that you can get from Toolstation and failing that batten and overboard the walls but mine has just been fully plastered so thats a last resort.

Pictures, plans, damp tests would be nice 😉 … You mention a chimney wall, these can often cause issues, over the years tar, crap and salts get into wall, any previous or current water issues can push salts through wall, later on the salts can attract moisture and show up as ‘damp’ patches. Not saying it is, but bear in mind.

Ideally test the wall using a Calcium carbide meter, but use a proper one and test for nitrates/sulphates too, might need a professional (meters cost a fair bit, do not use the two prongs electric timber meters in walls;)

If you have a relative humidity meter, see what it reads when it rains, our old house can show 90% RH inside and show damp stains do happen, at least that’s one reasoning.

Having said that I have also seem damp stains onto a dot ‘n dab wall, water coming down masonry and leaching through dabs, so might be worth making some holes to investigate. Good luck.

I never re point chimneys if there is no lead trays , two trays with at leat 100mm past brick work as fitting new step flashings and aprons / back gutter will not solve the problem. Have you asked your neighbor if they have the same issue ?

The only way to make sure water is not coming down the chimney is to take it down and rebuid and incorporate a lead tray  with weepvents.

I solved a similar problem on a previous property by bonding a large piece of lead over the top of the chimney with about 150mm overhang.

Cavity is probably bridged either with mass of mortar, brick, etc. I would cut a tidy hole outside and check, easy to do and repair if engineering brick without an untidy patch but if harled not so easy

Hey bn, Im with what @dti says, chimney tray has gone porous.

Couple of questions, is this on an internal or external wall? Im getting confused.

If external, is the chimney flue on the outside?

Did you mention you had the chimney repointed? What bit? Was damp present prior to this work?

Pictures might help 🙂

I’ve had an issue on a cavity wall after building work where a door had been bricked up re plastered inside. The problem was water coming through the outer bricks and then bridging via the cavity wall insulation to the inner wall. This only showed on the new plaster, the rest of the inside walls were rendered before a final skim of plaster which prevented any problems being visible inside. The walls had all been re pointed and sealed with Thomson’s water seal when the work was done but this didn’t prevent it. The answer was Facade Cream, a tip off here I believe. Expensive stuff but works brilliantly, could well be worth treating the external part of the chimney, nothing to lose but money 🙂

<Long post warning>

Thanks for the replies folks – some interesting thoughts and I’ve taken some pics which I hope will help illustrate the issue.

Weirdly, and predictably being this house, it doesn’t always come in every time it rains.

I dry the area out at night using the woodburner at the moment, so I can then conduct various experiments with a hosepipe (phnarr) to try and replicate the issue.

After last night’s pollution-fest, after a night and day of continual rain – nothing. No sign of water at all.

Which leans me towards maybe it’s only when it rains with a prevailing wind to drive it in somewhere at an angle. Roofer (a good one at last) is pretty insistent there’s nothing wrong with the chimney though and actually suggested so before I had the flashing redone.

I’m going to have to google some of the other stuff about porous trays and the such-like. Loathed to spend more on rebuilding the chimney without being sure that’s the problem. I just can’t think how else it’s getting into that wall….

Anyhow, to the pics:

This was Friday after some rain. It had been dried out the night before. (You can see the dried out marks to the left which is when it’s at its worst)

The yesterday afternoon drying it out again in readiness for last night & today’s rain.

And just now. The fire obviously continued to dry out and there’s been absolutely nothing as you can see. It’s rained continuously pretty much for the last 18+ hours.

Adjoining wall in question:

Chimney outside

Chimney inside

Damp patches at bottom of plasterboard. I’d already brushed the salts away.

*cries a bit more*

..and finally a dumb question, would the adjoining wall actually have a cavity?

Thanks again for experiences so far 🙂

Just had another thought…..when the water becomes visible at the front of the hearth, it actually gets damp from right to left as time goes by…..and then dries from left to right accordingly..

…which seems odd if water coming straight down?

Thanks for those pics, may not be the tray.

Does the damp appear in the chamber as well as at the front and on the sub hearth?

Could be that the slate type damp course supporting the chimney breast, sub hearth and party wall has broken down? If it had one at all?

Damp is a result of little or no air movement, with a suspended floor this is encouraged, although if the ventilation bricks are non-existent or blocked with debris, or not enough of them then the damp has to get out somewhere else, preferable route is through the driest medium, which will be around your nice warm and dry fireplace…

under the gutter where the walls meet is that water staining on the white wall? Is there an overflow pipe as well?

The chimney breast in the roof void is showing some salts and (possible) damp stains. Have you checked to see that its dry?

Edit: the party/separating wall is almost certainly 225mm solid brick. But, looking at the bond (lots of stretchers and few headers) there could be significant pathways for moisture to travel downwards.

.

Is the space between the top of the stove liner and the chimney pot filled with cement? You would be surprised how much rain can get driven in a pepper pot.

If it isn’t sealed with a lot of cement, do so. That is what was causing damp walls in my terrace.

whats happening to the wall under the floor?  wet too?  im guessing its damp coming up purely because it has to come down a long way and no sign of damp above seems most unlikely in my mind.

adjoining wall unlikely to have a cavity.

Thanks again everyone – it’s all helpful

Yes, bricks under the floor have plenty of signs of salt and the ground is damp (but ventilated) so it points to water entering, hitting the floor and seeping up….WITH….the fact that when it’s raining – sometimes/usually – that patch around the hearth can become damp pretty quickly – within the hour.

The cowl isn’t cemented in, no…..another avenue to ponder then (although the problem existed pre-woodburner)

This wall didn’t have the Rentokill DPC fitted 30 years ago, which would explain why the damp is seeping up from the ground only on this wall, but not why it’s making its way into the house into the first place (sometimes) when it rains.

The chimney inside the loft is dry, but agree in that the salts make me suspicious too.

And someone’s observant – no it’s not a water stain, just a bit grubby (assume because doesn’t get exposed to the elements) but that is an overflow pipe of some sorts. Don’t know what for – I assume the house had a water tank in the loft at some point.

DPC install

And yes, I’ve got a part solid concrete floor in the kitchen. **** knows why! I’m assuming something something coal, because there’s a random stone lintel on the exterior wall about 3ft up.

Sorry, too late to edit but yes, there are signs of water presence at the back/side of the hearth too but that’s trickier to judge in relation to rainfall. Also the stove is convection, so doesn’t radiate much heat to the side or back so not as easy to ‘reset’ the actual hearth dampness and then monitor.

I worked on a house recently that had a very similar problem to yours – water appearing around the bottom of the hearth and damp patches in the plasterboard to the left of the fireplace next to the woodburner. Problem increased in rain but specifically when it was windy from a certain direction ie it was getting driven in at an angle. The house was also on the top of a hill. Water got in between flue liner and chimney and ran down where it collected on the register plate before then making its way behind the plasterboard. Do you have a register plate? Have you looked to see what the top of it looks like? The flue liner was attached with a bracket on the pot only, it seemed unlikely but water could get in under certain conditions.

My other suggestion is to go out when it rains and check that all the rain goods and rones are running properly and no water is running onto the masonry. As I type this a house over the road has a massive wet patch on the stonework caused by a tv aerial cable that lays on the roof tiles. It diverts and collects rain which then runs down the cable to the point where the cable enters the house. It then drips off the curve in the cable and soaks the stonework and pointing.

I can’t believe no one has mentioned this yet, but then maybe you lot don’t have the same sort of insight I do. It’s not water at all. It’s ECTOPLASM.

Now, you can either call the Ghostbusters, who are both expensive and ultimately not that competent (remember what they did to New York), or you can call me.

£100 and I’ll get it all cleared up. No more ectoplasm, and you’ll have saved a wack of cash.

Email in profile.

That’s a really interesting perspective thanks, another +1 to look at the cowl then, but it’s been an issue before that was installed.

I do have a register plate and now I’m pulling the hardibacker off I may as well pop it off to have a peek.

You’ll have to tell me what rain goods & rones are though – I’m assuming a typo that I’ve not deciphered! 🙂

The valleys are knackered too and need replacing (and I will be doing) but I’ve assumed that would make itself known in other walls upstairs if causing a leak – even the one running down to the wall in question would have to be making the upstairs damp too….wouldn’t it?

(And yes, I live in the chocolate of the Neapolitan ice cream family of houses 🙂 I don’t think any bloody house has been posted on STW more – I’m sick of seeing it here myself! )

bearnecessities wrote

The valleys are knackered too and need replacing (and I will be doing) but I’ve assumed that would make itself known in other walls upstairs if causing a leak – even the one running down to the wall in question would have to be making the upstairs damp too….wouldn’t it?

Ah now, if valley is leaking water could be down pitch of roof running into cavity.

edit is the room with damp at front or back?

Any idea what the flaunching  is like on top of the stack/around the pots? Those pots could extend quite a distance downwards into the stack: Water penetrating down around them could transfer onto the flue line and continue down. Agree with checking the top of the register plate: perhaps after rain?

Where does the other flue go, into an upstairs room? If so have you had a good check around  inside that fireplace (if it’s accessible)?

The living room runs from the front to the back. I’ve tried to illustrate below.

Flaunching has been completely dug out and replaced. The other flue goes into upstairs bedroom, to an unused fireplace. Not the slightest sign of damp anywhere.

Ah yes soz, rones are gutters and raingoods are everything the rainwater runs down – down pipes etc. I’m in scotland, regional variations may apply!

I’ve never heard of flaunching either, i’m assuming that means the haunching around the pots and between tiles and skews!

Skews? 😂

Running out of ideas here. That stove flue terminal looks very open. Wind-blown rain could get into that and run down. Back to checking the register plate.

Oh, and I assume you gave checked the bathroom above for any leaks which might get into the gap behind your plasterboard drylining.