Hi
My house is under erm...medical attention at the moment, and amongst quite a few jobs is a damp patch under the stairs, it is on an internal wall, but is the otherside of an external wall, and has about a 15-20inch black patch - I know this to be damp - just havent a clue how to treat it or sort it, any tips etc would be great, thankyou in advance!
Alison