On Jun 5, 3:51 pm, "Will" wrote:
"TMC" wrote in message

...

thanks for your reply.Top posting removed

yes, I guess that's the difficulty. The damp patch is directly next to the
door frame (into the kitchen), about 3 feet up from the floor.
The walls appear to be solid. I'm not aware of a cavity of any kind. It
would be a pretty unusual place for a pipe I think.
A leak at the top of the wall might be a good shout though, as part of the
drain pipe looks like it's collapsed, and it might be possible that water
from that could be running onto the wall. I had discounted that before, as I
damp patch was in an unusual position.

It is a leak from the new bathroom flowing down the line of least
resistance. Probably a tap or shower/bath outlet weeping. It has
descended the frame and hit the wooden wedge that was used to fix the
frame.

From there it has been directed into the wall and is oozing past the
wooden wedge and into the masonry. Just find and fix the leak and it
should dry out no problem in this weather.