damp patch on chimney breast

[john.s]

I have a damp patch on the chimney breast (internally) at about half way up the wall. I have been told by a couple of people that rain water is most likely leaking in from the flashing around the chimney. I'm poised to go up and have a look but don't really know what I'm looking for. I was up there a year ago fitting an aerial and I had a quick look for the cause then but could not see anything obvious. As I now need to finish decorating the room, I have to finally resolve the problem. Anyone got any tips?
thanks,

 

[another_richard]

It cannot be the flashing as the damp would then be top down and you would see it from the loft.

Is there a pot on to and if so does the pot have a cowling? I used to get water running straight down the pot and into the grate via the insert until we put a coling on top of the pot.

Is the wall facing externally? If so go outside and see what has been drilled into it?

 

[john.s]

Hi Richard thanks for the advice.
My chimney is a bit unusual because as soon as it leaves the ceiling it goes out through the roof, due to the way the roof is pitched. So there is nothing to see in the attic. The damp patch starts at the side at the top of the ceiling now I look, and comes round to the patch at the front. The patch is left of the fireplace, but it is straight under the chimney pot, (the last part of the flue to the fireplace is angled) so maybe water could just be coming straight down the chimney. There is a chimney pot but nothing over it - and as I want to use the chimney for a real fire I thought I would keep it that way.
Is there any point going up on the ladder again and trying to spot anything. There is nothing drilled into the wall, but I did put two large brackets in with bolts onto the chimney, to hold a large aerial pole - the problem was already there though.

Hopefully the picture above will explain it a bit better - if you look in through the little window the damp is on the chimney breast just inside there.
Thanks
js

 

[Cloudscape]

Is something growing on top of the stack? Roots could open up gaps in the flaunching - the 'mortar' cap.

I had a problem with a damp patch on one side of the face of a chimney breast. It was caused by the rain coming down the chimney and dripping onto a change of direction in the flue - an angled platform. I could sometimes hear the dripping. Eventually, it showed on the surface. The flaunching was cracked.

Damp up by the ceiling seems to suggest the flashing is leaking, or could it be backwards overflow from the gutter?

 

[john.s]

Yes the whole side of the building right up to the chimney top was covered in ivy - I removed it all (well, nearly all - the last bit you can see is a dead bit I could not reach) when I put the aerial up - I bet that is the cause! It had ingresed in a quite a few places, but I had forgotten about it.
I will go up there plus check the guttering while I'm at it - I was going to do all the gutters anyway.
Thanks
js

 

[Hiriaeth]

You can still have a cowl and run a fire. If you are in an exposed area or get alot of rain it is suprising how much goes down the chimney. If you are not having regular fires then the chimney then never gets a chance to dry internally. Is the flue Lined? If so is the lining a cement one that may have cracked and letting in water which then is trapped and comes out in the room? Also may be worth checking that the junction between the pot has not got a crack where it is attached to the stack, water could get in here perhaps.
If the flue turns water may be landing on a ledge and soaking in (doesnt sound to be the case with yours though).
UFO Style cowls are ugly but stop alot of water except where very windy, H Pots are better but steel is ugly, could you find an old clay H Pot to use? May need to check what youy can use for buildings regs don/t know if you can use old cowls or not?

Or get a steel flue put in, doesnt actually change the buildings character, chimney stack still gets warm but it stops water hitting the walls.....
Good luck!