HELP PLEASE: dripping chimney that can’t solve

26 Dec 2017
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United Kingdom
Hi guys,

Please help me, I’m desperate for some advice. We live in an 1890’s mid terrace with an open fireplace into our bedroom, when we have rain we get drips coming straight down the fireplace and into the bedroom and I can’t for the life of me work out where the water is coming from and it’s driving me mad hearing the drip drip drip!

We have had a roofer come out and do some work on the problem and it’s still leaking as he can’t find where the problem is but he did some precaution fixes to try and stop it. We have 2 gas cowls that sit on the top of the chimney which are in good condition, the flashing is in good condition and the roofer confirmed that the pointing all looks ok. He built up the flaunching (think that’s how it’s spelt) to stop any cracks in the crown or any leak coming in from the top or around the cowls but it is still dripping in when we have rain or snow!

Any advice on where it could be coming in from or what to check as it’s dripping directly down the chimney cavity and into the open fireplace? I’m starting to going mildly insane!!

*i have uploaded a pic of the chimney in question but I can’t get much closer sorry.
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Check/ renew the flaunching around the pots. This is the most likely.

Fit a pot with a cowl.

Have the chimney swept.

Always ask for photos of the work before and after for roof and chimney work
Thanks woody, the roofer did the flaunching and built up the crown so it was all brand new cement. We have gas cowls and he checked the condition of them...there was nothing wrong with them. He showed me pictures of the before and after and I can’t see where else the water can come in from.

Any other ideas?
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It's possible that the rain is slanting in the wind, and getting in through the sides of the cowel.
most likely as said its the flaunching. the top 5 or 6 courses could do with a rebuild.
you show two terminal cowels but there should be min of four .
you and the next door share the stack and the roof join. your ridge an roof joins look a bit strange but its hard to tell. is there a bonding strip? at any rate i.d agree definitely its the flaunching.
wheres the before an after photos that have been mentioned
Looks like your neighbours have been re-roofed. Their flashing is cut into the brickwork bond one course higher than on your side. How 'good' is the sealing of the join between your roof and their roof? Can water running down the roof above the stack be getting past the flashing? - it should be one peice on the high side (ideally of code4) which the roofers should have done when the roof was worked on.
Is the flue in question the the closer chimney pot to you in the photo or the further one?
I'd question how good the work on the flashing is on the hidden side of the stack - that could be the water ingress route into the flue; especially if the problem chimney is associated with far pot.

I'd also question what the chimney pots have been capped with? I doubt if they are proper cowls for use with fires (of any type). They look more like 'pot crowns' which are designed just to provide enough ventilation to stop condensation, not be big enough to allow a fire to burn properly; also from the picture the vents look blocked.
Hi guys, thanks for the replies. I will try and answer as many questions as I can but I am no expert. So in the photo our stack is the nearest to you in the photo, the one with the metal gas cowls, next door have these half tube shaped pots that lay on top of the stack on their side...could that be where the water is coming in? I don’t have the before and after photos from the roofer unfortunately. He did say that he checked all the flashing and it was fine, he also checked the pointing and that was fine...we haven’t had any water coming down the walls so I guess it can’t be the flashing or pointing as it would not drip directly down the chimney, it would come down the wall instead. The roofer did say he could block up the gas cowls but that would be dangerous as their is a gas fire downstairs.

The roofer did a good job of covering the crown around the cowls so I am now inclined to think it’s coming in from either next door or the cowls themselves.
Flues are separate so it's unlikely the source is from next door.

Generally, rain does not tend to fall straight down a flue due to air currents, and as a chimney is masonry, any random rain drops are absorbed when they hit the sides of the flue.

Therefore drips tend to come from defects in the small area of flauncing immediately around the pots (smaller diameter round pots underhang wider square flues), or defective pots.

If the flue is a metal liner (which may be so if you have metal gas cowls) then drips are common if a gas fire is not used.

Caked on shoot or a projecting snot or brick in the flue can also provide a ledge for drips but this is much rarer. But this can become an issue if condensation is forming in the flue - possible if you don't use a fire, and if the cowl is undersized to draw air out.

Defective flashing won't allow water into the flue. That shows up on the outside of the chimney in the loft and rooms below.

One other potential thing to check for is a crack in any horizontal DPC above the roof line. But a stack of that age probably won't have a DPC in it.

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