We moved into a Victorian terraced house a few weeks ago, which was renovated by the previous owners. Since moving in (was not present on several viewings of house) damp patches have started to appear on the rear wall.
The wall has been newly plasterboarded and painted. There is a long damp patch (4 feet) where the ceiling meets the wall, that runs about 2 inches down the wall, as if the water is slowly moving downwards, as well as several lighter damp patches at various places in the wall - a couple round the skirting board (which we've removed and cleared debris that was breaching the damp proof course but patches remain), patches around the back door recess and some mid-way up the wall.
The patches appear to get worse after periods of heavy rain and I think are cause by rain water penetration. We have what appears to be a square lead box gutter that runs to a downpipe at the side of the house. The wall is south-westerly facing and we are on a hill and it seems to get the prevailing weather (rain sounds much worse than at the front of the house). During heavy rain, dripping can be heard with water dripping from the ground, first and second floor window sills. Visually all the mortar/pointing and windown seals look fine.
I want to get a roofer (is that best person?) to check gutter for leaks/blockages and then we planned to leave the wall until the summer and seal the exterior with a waterproofing sealant. Is this the right thing to do? I've heard it can stop the house 'breathing' and make things worse?
Any other suggestions?