I originally had damp in my living room on the chimney breast wall, which I got a damp proofer out to fix. However my problem is there are patches appearing that look like damp marks coming through the plaster but are not wet (they look a bit like a grease mark). The damp proofer has since been back out and re-done the damp proofing but the marks are still coming back through, to which they have said it is something to do with soot in the chimney and water coming down the chimney. I have just had a chimney sweeper look at the chimney and he feels that this is not the problem as the chimney is clear. Do any plasterers know or have seen this happen before and how to fix it? Thanks Kate
