Leaking from chimney stack

[thedigger]

Hi, apologies in advance for the vague information given!

We have a 1920s semi, where the chimney breast has been removed and supported on gallows brackets in the loft. We have occasional stains on the upstairs ceilings, but after heavy rain last night (Storm Angus!), I've noticed a new massive wet patch.

I've gone into the loft to rule out a slipped slate or plumbing issue, and the only wetness I could find is in the insulation directly under the chimney breast, which is also dirtied with soot which suggests water is coming down the remains of the chimney.

The chimney breast was removed (and presumably the top capped?) by previous house owners, but do these have a habit of working loose? Or could I have a potentially bigger problem on my hands?

What I'd like is to fully remove the 4 chimney pots and render over the holes - is this possible/legal, and is it an expensive job? And would this be a builder, a roofer or a chimney specialist?

 

[vinn]

Removing your chimney pots might cause you even more difficulties.

The condition of the stack flaunching, and the pointing of the stack brickwork, & the lead flashing plus the surrounding slates need examining by a roofer, and photos to be posted on here.

If all the above are in good condition then clay terminals should be inserted into the pots to provide ventilation & prevent ingress of birds and rain.

 

[thedigger]

Thanks for the reply vinn. I don;t think it's the flashing personally, because the water is dirty and sooty so it must have come down the chimney rather than through a gap. Would damaged pointing allow water to flow inside the chimney? It's hard to tell what the pointing is like from ground level, but I think the next job is to get someone up there with a ladder

 

[vinn]

Both flashing and pointing can allow moisture penetration esp. if the stack has crumbling mortar.
Given you say that you have slates then if the roof has to be crossed ask for a roof ladder to be used or you might end up with cracked slates.
Why not post pics of the stack from below?

 

[catlad]

Its a misconception that chimneys are waterproof, when the chimney was in its original condition the ingress of water in the shaft couldn't be seen
but now the chimney breasts are gone it noticeable.
I have known people who have completely rebuilt there chimneys
with new brick and they still have problems because they have
removed the chimney breasts, that and they didn't put a lead dpc in.

 

[Doggit]

that and they didn't put a lead dpc in

Very few chimneys had a DPC because the chimneys were in use when it rained, and even if they weren't, a damp chimney in the loft didn't matter. When a loft conversion gets done, you need to (As Catlad suggests) either to rebuild the chimney with some sort of DPC, or inject a silicone one such as Stormguard, to the lowest horizontal mortar line, and then the perps as the roof rises, and then ideally, apply a waterproofer as well.

And yes, I've learnt the hard way.