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Chimney breast leaking

  • 12-02-2024 1:01am
    #1
    Registered Users Posts: 17


    Hi,

    I’m running out of ideas what’s causing damp/wet patches on second floor chimney breast wall. I installed new chimney cowl with new liner, I tanked external chimney, around chimney lead looks ok, in the attic all around chimney bone dry…only in the winter when bad rain hits season.





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Comments

  • Registered Users Posts: 5,156 ✭✭✭greasepalm


    If i see a crack on those photos what is up on the roof i wonder , when you said chimney was that the pots or all of the brickwork going down. Old brickwork can be like a sponge drawing it in.

    All brickwork needs is a crack to get drawn in as whats below shows.



  • Registered Users Posts: 17 Roky2018


    External chimney bricks is in good condition, as I said its fully tanked around , crown been tanked 2, there is no single crack on the chimney or top…after I tanked I replaster chimney wall breast, I thought problem solved, but this winter problem a-pear again, not that much but still as you see on first picture.



  • Registered Users Posts: 17 Roky2018


    May same one had same issue?



  • Registered Users Posts: 2,318 ✭✭✭Field east


    A few relevant photos of the chimney from the outside might be more informative



  • Registered Users Posts: 17 Roky2018


    Pictures



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  • Registered Users Posts: 2,690 ✭✭✭niallb


    What goes up the chimney?

    Is it an open fire, stove, or exhaust from a boiler?

    If it's a boiler have you had it upgraded in recent years? Modern condensing boilers have much cooler exhaust which could condense inside the chimney and seep into any crack in the lining.



  • Registered Users Posts: 17 Roky2018


    I got insert stove with liner installed all way up…all summer perfect was, before heavy rains started.



  • Registered Users Posts: 368 ✭✭Doolittle51


    Could the issue be originating further up the roof? Water coming in at the ridge for example could travel down the felt and cause damp where it meets the chimney.



  • Registered Users Posts: 17 Roky2018


    I lifted last summer lead and tiles, I seen same stains around, but didn’t see any noticeable dampness….just my thought’s, if lead fails, I would be seeing marks or stains in the attic, but attic bone dray around the chimney …



  • Registered Users Posts: 6,311 ✭✭✭10-10-20


    How is that lead flashing bonded to the render? Was it cut into the render and then fitted into the slot, or is that just lapped up-to the render and then bonded directly using the lead flashing filler - I can't tell from the photos.



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  • Registered Users Posts: 17 Roky2018


    I think it was lapped up and rendered on the top…



  • Registered Users Posts: 17 Roky2018


    Same pic.



  • Registered Users Posts: 6,311 ✭✭✭10-10-20


    Then in my opinion that's the most likely cause of any leak. The lead should be cut into the render/block and then sealed.

    Example in the initial images here:




  • Registered Users Posts: 17 Roky2018


    What should I do? Take them out all together and if there is no cut in, than do flashing with cut in all around? How deep to cut? Do I need hide flashing lead with the render couple mm?



  • Registered Users Posts: 17 Roky2018


    Thank you for advice…but just wondering how water could go behind??? It’s all way down tanken fully even lower bellow flashing.



  • Registered Users Posts: 17 Roky2018


    Thinking loud, if that be the case as you saying lead issue with chimney , means I would be seeing damp patches or satins in attic on chimney bricks?? But there nothing



  • Registered Users Posts: 6,311 ✭✭✭10-10-20


    You added two photos which I hadn't seen. From them I think that the lead tray might be installed correctly as it's lapped under the upper section of lead which I'd guess is bedded into the blockwork. Only by opening the render at a point would you know for sure. 🤔

    If the lead is only bonded to the blockwork then It's actually the exact same as what's being discussed in this topic:

    The lead flashing only collects what hits and runs-off the exterior of the chimney but wind driven rain penetrates the paint and render on the chimney and the water tracks down the path to the base of the chimney, causing the leak.



  • Registered Users Posts: 33,158 ✭✭✭✭listermint


    From what I can see I think the lead needs to come out. Clean behind and redress. Probably one for the drier months though I'd want some level of warmth on the brickwork.



  • Registered Users Posts: 6,311 ✭✭✭10-10-20


    That's the overlapping detail there that looks fine except what we can't see behind the render. If that lead lead is solid then I'd be thinking of running a hose over the tiles and just up to the base of the lead (on a dry day) and then see if it's leak at the lead and tile level. Then try wet the chimney after that if it still remains dry.



  • Registered Users Posts: 33,158 ✭✭✭✭listermint


    Seeing copious amounts of used silicon on that. Warning bells !



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  • Registered Users Posts: 6,311 ✭✭✭10-10-20


    Actually just spotted something... might be small.

    Does the upper lip of the lead at the left of this photo go right under that second row of tiles or is it border-line? I'm kinda still thinking that it's the render as I don't see water staining or rot on the battens...



  • Registered Users Posts: 6,311 ✭✭✭10-10-20


    True, but could just be a repeated attempt to fix something that isn't the issue. But I'd still suggest that only removing some of the render will answer some of the questions here.

    tanked external chimney

    Just going backwards OP... Do you mean tanked under the fresh paint using a bathroom tanking product, or what?



  • Registered Users Posts: 33,158 ✭✭✭✭listermint


    True. Good shout on the length of lead. Looks to be 20 mm on near side tapering over to 10mm on the further side. Very limited coverage under second row of tile.



  • Registered Users Posts: 6,311 ✭✭✭10-10-20


    A second thin sheet of lead or even DPC plastic wouldn't go amiss there.



  • Registered Users Posts: 2,690 ✭✭✭niallb


    Plenty hot enough so.

    Were you having damp problems before the stove was installed? That looks like a lot of water in the wall.

    Have you seen the seal of the flue liner to the top of the chimney and cowl? Water coming in there could explain why the attic is dry. I'm curious as my dad had a similar looking problem on his house and had the chimney rebuilt, part of the roof replaced and redecorated only to find it as bad as ever the following winter.

    In his case he realised that he'd removed some broken chimney pot pieces from the fireplace much earlier and that some must have hit the angle on the chimney on the way down. He's an engineer and one back of an envelope later realised how fast it would have been going at that point. The crack was about halfway up and resealing the chimney and fitting a flue solved it permanently for him.



  • Registered Users Posts: 6,311 ✭✭✭10-10-20


    Exactly, capping stone or such isn't mentioned.



  • Registered Users Posts: 5,156 ✭✭✭greasepalm


    Photo in post 20 i can see a gap to the right of red marker going down the roof . Also agree on the iffy silicone put on



  • Registered Users Posts: 3,930 ✭✭✭spaceHopper


    A good roofer will have this sorted for you, and probably won't cost as much as you think. Had two leaks in my roof fixed for 300 euros in about 45 minutes. Granted it was cracked tiles and easily fixed. Your's will take more.



  • Registered Users Posts: 1,558 ✭✭✭Squatman




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  • Registered Users Posts: 17 Roky2018


    There is 2 coats weather proof slurry applied and painted on the top external chimney …there is no chance even drop any water from lead tray couldn’t penetrate in to wall…



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