About 1 month ago I had a damp proof course (dpc injections) installed to the ground floor of my 1800's terraced house. We have been advised that we need to have the plaster hacked off and replastered as there are damp stains to some areas of the walls. I have been looking at products such as Thompsons Damp Seal which say they cover the stains, allow the moisture to evaporate and that's it. If this is the case why do I need to get the plaster hacked of the walls and replastered? Does this product not do the job at a fraction of the cost? I am hoping someone may have some advise they could offer on this dilemma?