Damp wall. Could it be a leak in the roof?

[bullethead123]

Hi all,
Last year I had a damp patch in an upstairs back wall just below the height at which the back addition joins the main house. I got a roofer in and he replaced a few cracked tiles and some rotted felt which seemed to fix the problem.
Now I have 2 damp patches in a downstairs party wall which get noticeably worse when it rains. could the two be connected? The roofer having fixed one problem and then the incoming water being 'diverted' to another wall? The neighbours have no damp at all on their side of the party wall.
As can be seen from the pictures below, the damp patches start approx 1M up from floor level and are separated by the width of (what used to be) the chimney breast. Someone mentioned to me that it might be 'rising damp'. Would this be a possibility given that the dampness is much worse when it rains?
One other contributory factor could be that there is a leak in the pressurised hot water system. I know this because I have to recharge the system from time to time.

 

[KenGMac]

bullethead123, good evening.

About this unused fire place and chimney flue??

Does the chimney still rise above the roof line? and if so are all the chimney pots capped off with vented caps?

Any idea what the lead flashing around the chimney head [if one exists] looks like?

As for "Rising Damp" if it was rising damp I would expect to see the damp patch, which appears pretty pronounced to go right down to the top of the timber skirting.

Are there any Central Heating pipes anywhere near this wall in the rooms above? or a radiator on the same wall above??

Ken.

 

[bullethead123]

Hi KenGMac, and thanks for your input.
Yes the chimney stack is still there and I can see two (of the four) pots. Both have what I would describe as 'inverted Vees' on top of them. I guess the other two do as well but I cannot say for certain.
There is no lead flashing around the chimney stack, instead it has some cemented in tiles. I have been up a ladder (but not on the actual roof) and, from what I can see, this seems to be in good order.
There are no rads on this wall upstairs or down but there is a rad upstairs one pipe of which enters the floor 5 inches from the affected wall. There are no signs of damp on the ceiling immediately below though.
I have had to periodically 'charge' the pressurised central heating system with water for the past couple of years. Could this be the source of the damp? If it is, is it likely to be from above? The room above is carpeted and so it would be a problem to inspect the floor void.

 

[KenGMac]

bullethead123, good evening, again.

Sounds as if the chimney pots have rain [proof] vented caps, so all good there.

The cement [so called] Flaunching can be a problem, in that lead is a really good flashing lasting at times for a very long time, Cement on the other hand does tend to crack and admit rain water.

What condition is the chimney stack in? is there any indication of missing pointing or any indication that any of the brick has spalled and the face of the brick dropped off?

Is there any access to the loft space? if so can you see the inner surfaces of the stack within the loft area

Finally, is there a room vent into where the old fireplace was situated? The reason for this question is that OK there may be a vented chimney cowel that stops rain water entering the Flue, But? if there is no actual air floe through the entire chimney flue, Condensation can occur within the flue and cause dampness on the walls of the room. OK your issue is not a "Classic" area for flue condensation, BUT???

Ken.