Chimney leak - what's likely to be the culprit...

Hi,

Over the past few weeks, i've noticed that there is some water getting into the wall behind our chimney stack on both the ground and first floor of our house, which has stained the plasterboard. I've been able to get some photos of the chimney and from first review it looks like the crown is cracked, which may be the culprit. However, there appears to also be some weather damage to the rest of the brick work on the chimney. Do you think i could get away with getting the crown sealed/replaced? Or do you think there are further repairs to be done to make the chimney water tight?

If additional work may be required, what would you think the best course of action would be?

Some photos of the chimney are attached to this post.

Any help would be much appreciated.

Chris.

Check the roof and lead first, looks like you have a broken tile at the back of the chimney.

The bricks are frost damaged this won't go away.
Liklely it has be made worse by the condition of the chimney head allowing water into the stack and not escaping through the cement pointing.
Rebuild the chimney or repair the head with a cowl.

Thanks for the reply guys, much appreciated.

Since i've posted this, i heard a dripping behind the wall which seemed to be hitting a surface about chest height (On the ground floor). I've just cut a small hole in the plasterboard to see if i could mitigate the leaking and there seems to be a lot of black residue (Possibly soot?) and a soft material (possibly clay?). It seems the water is dripping down from above and hitting this soft layer.

I'm going to get the roof and flashing checked again first thing next week.

Would it be possible for the water to get into the inner layer of the brick work to cause a drip from the top level if it was coming from the cracks in the stack itself?

you have a single clay flue terminal, aka a chimney pot, - the pot is cracked.
there's a flue vent inserted in the pot - these inserts vent redundant flues.

the flaunching is cracked, and inadequate.
moisture is streaming down the stack and staining the bricks, &, as above, causing frost damage.

the lead back gutter is inadequate - the back gutter should provide about 500mm of clear surface for the roofers feet, & be self draining.
your narrow backgutter is choked with tile debris and years of moss thats become a soil like sludge.
backgutter's sit on a wood platform.

1. first option is to drop the stack down by six or seven courses, and build a 40mm to 50mm projecting platform for new adequate flaunching, and a new pot with the insert vent.
2. second option is to re-new the pot and flaunching, - the flaunching must be built off a projecting platform.
3. re-point the stack or selected areas of the pointing.
4. is not an option, the back gutter and surrounding tile must be lifted to expose whatever is going on below the backgutter.
a new 500mm platform must be built and some of the surrounding tiles cut back to suit the new backgutter.

the water damage you've exposed in what looks like the original fireplace could be dropping down the flue from the inadequate flaunching - or, if you have Dot & Dab, it might be running down the chimney breast from the back gutter?
the RH side of the pic shows what looks like previous plasterboard/skim repair work?
can you look up and see a flue?
please clear all the debris and do another pic.

I've taken away a bit more of the drywall and cleaned up the debris so that i can dry out the wall. There appears to be a lot of soil/soot piled on top of the "dot and dat" plaster, which seems to be collecting a lot of the moisture.

I'm not able to look up the flue as the chimney itself is closed off.

Given the amount of soil in the wall, is it likely that the issue is with the back gutter? I.e from my first photo, it seems like there is a lot of soil/residue lying on the back gutter. Could this be dropping down into the house and through the gap between the drywall and brick?

why not cut away all the D&D p/board 300mm beyond the left hand and right hand sides, and about 900mm above?
and then totally cut out the P/board thats blocking the old fire opening?
remove all debris including the "soil" and clean up.
then see if you can photo up the flue?

what opinions do you have about the other items i mentioned or suggested in my first post?