Hello,

We have a constantly soaked external wall but only just nticed this when we spotted discoloured, cracks in the plaster on the inside just below this damp patch. The damp area begins directly below where the soil pipe emerges on the external wall but there are no obvious leaks or drips. I've had a look at the soil pipe on the inside and it seems fine so I can only assume if it is linked to the soil pipe (and not just a coinsidence) then the crack maybe in the external wall and be slwly seeping into the brickwork..

Can anyone shed any light on what this problem may be?

(please see attached pic)

Thanks

I can only assume if it is linked to the soil pipe (and not just a coinsidence) then the crack maybe in the external wall and be slwly seeping into the brickwork..
Or it could be the other way around. If you can't spot any leaks from the soil pipe then perhaps it's coming out of the bricks themselves. Let me explain.
I had a leak coming down the inside face of my fireplace and out the ceiling.
I tried for over 10 years to track it down. I had two roof companys out and they couldn't locate it either. Finally, after years of patching my ceiling and putting pans around the fireplace every time a storm came in from the South, I found it.
My house is over 50 years old and the mortar between the chimney bricks had shrunk allowing the rain to enter. The water found its way around the cracks and fissures and came out on the ceiling and down the face of the fire place. Caulking the joints and painting the chimney with waterproof paint finally repair the leak that had bugged me for so many years. I offer this as just another way to look at your problem. Good luck, Tom