Venting disused chimney flues…

[Gordon Fleming]

I’m not expert but I agree with you in so far as thinking the rain will be splashing up off the flaunching and in through the holes. Also The one on the right is clearly set too low (or the flaunching is too deep).

It’s equally possible that water is getting in from the ‘old’ side , presumably your neighbours side, and tracking across to your property. You might be better off just paying to re-do the entire top including your neighbours side. Possibly even repointing thier side too. I mean ask if your neighbour will contribute but budget for doing it all. If there’s no water getting in to their side then they have little incentive to do anything.

[Helen Green]

A better way of doing this is to fit an airbrick in the wall of the chimney, and then to replace the whole cowl/flaunching arrangement with a flat concrete slab

[George Anderson]

Needs chimney pots installing then the weather cowl on top, that’s not ideal with just the weather cowl sat on top of the chimney stack, flaunching & pointing needs redoing too, its holding moisture, that’s why there’s vegetation growing out of it. Maybe the lead flashings & saddle to the ridge, which we can’t see in the image provided.

[Simon Fitton]

thanks. I’ll do that. The leadwork has been done fairly recently and despite looking shoddy it at least seems to be serving a purpose (I had a camera up the chimney to identify the source).

[Henry Smith]

those pepperpot caps are designed to sit atop chimney pots not at flaunching level. Reistate pots and then put those where they should be. And remove and redo the flaunching completely and point any gaps (especially top bricks), don’t just patch.

[Simon Fitton]

I don’t have enough money right now for scaffolding and to lime point it. I do know I need to sort the leak out as a priority before the ridge beam rots through and was contemplating getting a cherry picker and redoing the flaunching/vents. Do you think that would suffice short term and is there anything else I could do whilst up there or would you advise just leaving the pointing alone until it can be done properly? Should I perhaps try getting the concrete off while up there?

[Josh Immes]

The coursed pitched faced stone work wants pointing in my professional option, it’s been overpointed with an extremely harder mortar than the sandstone & strap pointed causing water traps & ingress on the top of the pointing thus creating freeze thaw in the winter, which you can clearly see in the image provided where the faces have weathered back but the pointing in places is still intact. Also wants some stone indent replacements. In this senario I’d probably suggest a feebly weak NHL 2 with a graded river sand & ash pozzolan or a feebly weak 6/1/1 sand/cement/hydrated lime…needs to be a mortar that’s feebly weaker than the stonework really.

[Simon Fitton]

Yes!, It’s due to a multitude of things, capped over causing sweating in the flue due to different air temperatures & no air flow…holding moisture in due to the wrong mortar & terrible strap pointing (should be flush pointed to the arris’s (edges)…

[Ian Brown]

The vents are fine, but they need to sit on pots to raise them above splashes. The flaunching certainly looks like it needs redoing, and probably some repointing?

[Helen Adams]

the stack needs refurbishing, from the pointing , the flaunching , I will bet the lead work needs doing , you need some short pots to put those caps on, if you just tweak about then you will not solve the issues and will end up putting the scaffolding up again, if it’s done correctly then it can be guarenteed ( unlike my spelling ) and will be good for 50 years

[George Brown]

The chimney could do with an overhang coping effect, so the water from the top drips onto the roof, all the water is running down the haunching and back in under the open joints below the large stones

[Fred Bramham]

The elephant’s feet are intended to sit on and in a standard chimney pot. Setting them in the cement topping just means that all the rain runs onto and into the porcelain and cement join where it can’t escape. Rethink this when you are up there.

[Frank Morgan]

With a surveyors eye, I see a multitude of issues.

A wet ridge beam is not caused by water penetration within the flue. It’s possible in specific circumstances, but unlikely. A wet ridge beam is a failure or bypassing of the weatherproofing junctions at the roof/chimney/verge. The condition of the stone and mortar gives strong clues on the possibility of bypass through and around the stone sufficiently to get to the ridge beam.

The Leadwork detail is not visible. I would start there.

The flaunching isn’t perfect but given the limited information you’ve provided, it wouldn’t be my main area of investigation.

If you can’t confirm the path, no point getting the work done as it’s absolute guesswork.

If you’re going to get any work done, get a specifier to write it and confirm works undertaken comply with the design. You’re going to need a contractor experienced in Leadwork, lime pointing and Stonemasonry. General roofers are not for this job.

[Simon Fitton]

Here’s the other side of it showing the flashing. It’s not a pretty job, but I hope it is at least functional. It was an area of suspicion, but when the sweep had the camera up the moisture seemed to be coming from above there

[George Green]

I would draw your attention to his perspective on the pointing. That combined with the pots would explain your diagnosis of water entering the flue. It is also totally normal for rainwater to get into the flue… ventilation deals with it.

It wouldn’t follow to me that flue moisture tracks to the ridge beam. That is likely a Leadwork and pointing issue.