The Natural Philosopher wrote:
JK wrote:



I'd suspect a bridged damp course frankly, or none, giving classic
rising damp/penetration.

None would be par for the course...must have been done on the cheap, it's an
addition built by the council in the 60's.



Check outside and see if the soil is above DPC level, and remove if
it is.


It is, but sadly any soil in the area is topped with a thick layer of
concrete right up to the edge of the house.




Even if no DPC exists, you can vastly reduce penetration by digging a
trench round the affceted area and filling with shingle, provided it
is
not in an area that is lower than local ground so it just forms a
pond :-)


I'm frightened that if I chisel away the concrete from around the wall I'll
destabilise the walls! The house is built on London clay so I have no idea
what the drainage would be like.

Would there be any mileage on stripping the plaster on the inside say up to
3' and painting something waterproof on the inside bricks then replastering?
Or would that just make the water com out higher up?

J