4 Roofers Couldn’t Solve This Damp Chimney. Can You?

Roger takes a look at a problem Carl Fielding has with a leaking chimney.

Here is Carl's message:

I am having issues with my chimney leaking in the attic.

I have had multiple roofers come and look and even had a re-roof done. I was told the issue was gone and even got the attic re-plastered, but the issue is still there. I have had many roofers say different things, from a "Porous" chimney to bad fitting of lead work.

After the many pounds spent and the many useless roofers I have had, I want to try and fix the issue myself. I would classify myself as a good DIYer as I have fitted kitchens, bathrooms, stud walls, fences etc.
I have got to the point where I am watching youtube videos on actually removing the chimney lol.

It would be amazing if you guys could do some videos on repairing an old chimney or lead flashing etc or even common roofing issues as well. Please have a look and see what you think?

Kindest regards, Carl.

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#SkillBuilder #DIY #homeimprovement

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[gypsygem]

So refreshing to hear a builder advocating lime mortar these days! Thank you for the video, Roger

[stevenharrison]

A few years ago, I had a similar problem with a damp chimney in the attic of our c1912 home. The builder I got in to examine it could find no problem with the structure, render, flashings, etc. The only thing he could suggest was a chimney pot cap to stop rain dropping down the chimney but he couldn't find a cap that would securely fit the oddly shaped pot. I made a cap from 6mm stainless steel plate, which I secured with homemade hooked clamps down the chimney. I also incorporated a 25mm galvanised wire grille at the top, under the SS plate to stop birds nesting in the chimney.
The result was a completely dry chimney (& one impressed builder). 😊

[TonyFisherPuzzles]

You mentioned a drone for getting photos. I used some plastic pipe I had laying around taped together with a camera strapped on the end. The flexiness meant it kind of hung over the ridge and pointed directly down at the gutter. A bit of trial and error but worked well.

[SBIGDTSM]

Roger, before even watching all your video, I was 99% certain it was driving rain getting through, I know because I’m a builder and have seen this a few times and even on my own bungalow.
I live at a 1000ft in rural Wales, we moved 3 years ago and was getting water on our lounge ceiling, stack was soaking in the loft, I redone the lead, repointed, re flaunched it, still getting water, gave it two coats of Thompson’s water seal (not as good as storm dry I know) and it’s been fine since, I do it every summer now.
Since then I’ve done it on other properties with the same results, you cannot underestimate how much driving rain will penetrate brickwork, they even call for minimum 120mm cavities here because of it.

[theskilledgardener]

Hi Roger,
Looks to me like the soakers are Not over lapping so instead of discharging the water downwards its going straight down into roof space. That indicates whoever did it doesn't understand the principle of flashings and there could be other mistakes with it out of immediate view. Met a few roofers who didn't understand about soakers.

[jonb]

It's definitely coursed stone, looks like West Yorkshire (where I am) or possibly East Lancs. That strap pointing was done all over in the 60s to 80s. The structural mortar is of course lime mortar.

[doobersigaming]

Roger - literally watching as I’ve a 1930s property bit of a leak down the inside of ours and thought “Stormdry” brilliant stuff would recommend to anyone but didn’t think it would be suffice on a Chimney! Your a legend fella 👍

[bilbobiggens]

Hey Roger, Difficult to say with that flashing but one thing I didn’t hear anyone ask is if the flue (s) are lined/unused/sealed off. It looks a bit too wet to be just condensation but if the flues are capped and the fireplace openings blocked off, there is a chance that (as it’s an internal chimney) cold air from above the roof is meeting warm air from the lower parts within the house and condensating. I work in building conservation and see damp chimneys from either ones lined with a flexi liner and register plate sealing the flue around liner or just capped top and bottom. They should always be vented whatever is in them so that warm air from inside travels up the flue taking moisture out through a vented cowl or even vents in the side of the stack. Other than that, as you said, the cement mortar will massively reduce moisture loss from that stack. Old houses need old materials. We spend many of our days undoing work like this.
I would say, redo the soakers and flashing all around, get that dirty pointing out, repoint in NHL 3.5 or 5 if really exposed and vent the flues…sorted!

[zeus]

I had exactly the same problem with our chimney, so much so I needed to catch dripping water inside the loft with buckets. I found a crack on the concrete plinth on the very top of the chimney so made a metal cover for that. Coated the whole chimney with Thomson’s water seal…..never leaked since. Interesting video, thank you for sharing.

[jamesmartin]

Another great video Roger, you could (and should) make a full series on common chimney problems. I’ve lived in properties where chimneys have been taken out badly creating structural issues, others that have leaked and been damped like this one. And I’ve found that some roofers don’t want to get involved and some builders just pass it off to roofers.

[brownnoise]

Sorry but to me that looks to be extremely poor leadwork. Too many people don't even know about Soakers or the need for substantial overlaps to keep wind driven rain pushing water up over Soakers if they are fitted, and around Corners, the only way imho to ensure that it is a good job, is to take it apart and start again from scratch. If ot is done properly, Roofers Tippex (Low Mod Neutral Cure Silicone) or Mastic are not needed. tbh, we need to start up proper Apprenticeships again, withbsome decent Roofing Courses at Colleges again. Our Apprentice was on the last Roofing and Slating College Course in Wales, believe it or not, and did an Exhibition Roof Competition at the NEC. He was the inly one who finished off the last course of Slates at the Ridge Properly and securely. The Construction industry is in a bloody bad state all around sadly, and not just in Britain and Europe, it's a Global Problem. Best Wishes. Bob. 😔

[edmundhodgson]

Hi Roger. Agreed about the pointing. Regarding the waterproofing (stormdry or other), on chimneys, its must important that the haunching and pot are absolutely weatherproof to prevent excessive moisture soaking down the brickwork and overwhelming the breathing capabilities of the paint on barrier as this can exacerbate the internal damp problem.

[alanjewell]

I got fooled by a damp chimney breast. I went up & repaired the chimney rendering, checked all the flashings, ventilation cap etc. And what it turned out to be was hydroscopic salts from 90 years of fires had saturated the fabric of the chimney. So in damp weather, it attracted moisture just as leaving a bowl of table salt out does. I largely resolved it simply by painting the chimney breast with Stainblock & ensuring good ventilation through the unused chimney to keep it as dry as possible.

[James..]

The biggest issue in general is most chimneys don’t get used anymore.
I had a job had looked couple times tried multiple things could not get it resolved then 1 time I went back up the the tiniest little pin prick on a welded corner sealed that sure enough resolved it water gets in anywhere

[davidgoodenough]

Great video Roger,

I'm with you all the way on the ribbon pointing. Not only can it lead to water ingress, it leaves the masonry vulnerable to frost damage. Another issue to bear in mind with chimneys is that leaks can wash hygroscopic salts (from soot) into the plaster. The salts then absorb moisture from the air keeping the plaster permanently damp even if the original leak is fixed.

[franknash]

Really useful video. I have been working my way through the same issue and had decided to use Stormdry next summer. Stupidly I have closed off the chimney to stop the draught in my lounge. So will also open up the chimney (hadn't thought of that before seeing this video).

[gdfggggg]

The stone/brick looks very porous, so pointing with a sand/cement mortar is probably not a good idea. Looking at the stain on the ceiling, I would think the problem is probably to do with the rear gutter. A couple of images of the back gutter may have made things clearer. I had a job where the gutter was holding water as it was blocked with organic matter, and when the wind blew the water went over the lead flashing and into the building.

[alanyoung]

I have only just remembered that I came across a similar problem to this many years ago in a loft room. It turned out to be condensation running down the felt (due to lack of roof void ventilation) and accumulating at the back of the chimney. Condensation could also take place near the top of the chimney breast itself as this will be relatively cold in the winter. Therefore, if the problem is absent in August its probably at least part condensation. If the chimney is used you would also get condensation on the inside as the warm rising air meets the cold building fabric close to the exterior. The other consideration is hygroscopic damps – the products of combustion produce many contaminants, some of which are hygroscopic and these salts may leach into the brickwork where they will absorb damp from the room – which may be humid. I noticed when last in France that they sometimes clad external chimneys with zinc to provide a rain screen as it is virtually impossible to otherwise prevent damp to a chimney breast which is only inches below a saturated stack.

[truxton]

I did up a house built in 1850’s and had this exact problem. Had a roofer up two times but was still leaking. After some thinking I came to the conclusion that the whole chimney was like a giant sponge. So spent £1500 to get the chimney replaced. Problem solved.

[mktrollop]

I had a similar issue on my chimney, different story, concrete block. The render had been frost damaged over the years a d water was getting in, wicking down and coming out in a huge wet patch in the wall, the concrete cap had gone porus as well I think, I re plastered it and built up what was missing from the cap, no problems since, I think part of the problem was the fireplace for that chimney had been blocked off for years and wasn't vented. I was redoing the floor in that room so I just broke into the old fireplace from under the floor, blocked it off in the room, and now we've good ventilation up through the chimney from under the floor, I think that has a good part in keeping it dry too.