Water Ingress Via Chimney Stack

[barmy]

Any ideas?
The chimney stack in the spare bedroom is showing signs of water ingress which I put down to loose flashings but when I checked in the attic the chimney stack is dry.

Could the water be coming down the chimney and then seeping through to the wall after it get pass the attic somehow? I'm not a builder and I appreciate that I will have to get someone up on the roof once the rain stops but they could for example say the chimney stack needs rebuilding when it could just need the top resealing.

Thanks
Simon

[retrocop]

Is the chimney in use? Have you checked for a blockage within the stack and below the attic floor level. i.e. bird's nest or other debris?

[Zacs-Master]

At what level is the water showing (next to the ceiling or lower down) / Is the chimney on an outside wall or an adjoining wall (if your house is a semi or terraced)?

[ummmm]

Is the chimney breast still in place?

[The Builder]

Commonest reason for this is lead flashings, but this does usually show on the surface right up under the roof covering.
You can often see the staining where the water has run.

So, in this case, it looks like water penetration.
I doubt if it's rain coming through the bedroom wall horizontally. There's often too much of a mass of masonry for that.

I would guess that it is vertical. That is, rain seeps into the chimney stack. The stack becomes waterlogged. Then it travels downwards. It can travel for quite a way, and come out somewhere in the bedroom.

Before we go any further, how old is the house?

[barmy]

The chimney is not in use and the chimney breast is in place
the water is showing a the ceiling and has now covered about 2 foot of the wall, paper is damp
Chimney is on inside wall, not the communal chimney. House is 1930s semi
Thanks

[The Builder]

As you probably know, unused flues should have some sort of ventilation. It helps in these kinds of circumstances.

A "rain hood" or something similar (clay pot-like thing with a cover to stop rain, and vent holes in the side.)

But, back to the plot... 1930s can be a bit of a transition time. Before that, stacks may have been built with a horizontal "tray" just above roofline. Probably pieces of slate.
This tray is like a DPC in reverse. It stops water going downwards instead of upwards.

It may have no tray at all, or the tray has failed. You usually get away with it, but with recent weather.....................?

Anyway, before taking down the stack and re-building it with a proper, stepped lead tray... Try this................

https://www.toolstation.com/feb-silicon-external-waterproofer/p56806?store=HK&utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&gclid=EAIaIQobChMIhfWk0eTs5wIVCLDtCh0MDgikEAQYASABEgINk_D_BwE

There are loads of other makes available.
I've used it a few times. A couple of coats all over your stack will do it.
If things improve, then you can think about a stack rebuild.
After all, I may be quite wrong. It may be something else, but this is a relatively cheap way of finding out.
The silicone treatment may well last for several years anyway.

[Palustris]

How very odd. We have just had a roofing expert in to look at our chimney breast because of water ingress. It is probably not the flashing for us. Rather is is that the rain is penetrating the stone work and seeping out at the lowest level. The answer is to let it dry out (if the rain ever stops!) and spray the stone work with Silicon. If that does not work then we may have to consider having the no longer in use stack removed. For us that would be one hell of a job as it is stone, not brick.
Best of luck to you. Simon

[KARL]

Chimneys and the fireplaces that give rise to them ought, in my opinion, to be the subject of a grant scheme every bit as aggressive as the ones for insulation - these things are a form of central cooling (still open) and/or a serious problem to any building. That leaves aside the fact that they are almost always absolutely pig ugly.

If you intend to, or end up, having major work done on the stack, and it is all yours and unused, then my recommendation would be to have it removed completely to below the roof line - the roof would then be closed over the stump with a minimal clear space between the two. After that you can completely forget about it. You would need no more done forever because the chimney is then just a void within a wall, completely inert, but presumably you would still have a non-flat wall where the fireplace was.

[Palustris]

Sadly our Chimney stack is part of the structure of the bungalow and cannot be removed. Even to lower it to roof level would be difficult. Our roofing expert shook his head when we suggested it. It would involve all sorts of structural alterations to the roof which could cause even more problems than the water ingress at present.

[KARL]

Palustris, I have to say that your description of the reaction you brought about strongly suggests that you need a better "expert". Even below roof level the chimney structure can continue to serve its full previous load bearing capacity. Connecting any radiating/converging structural members is a textbook challenge.