I had my ground floor flat completely refinished early this year. The walls were all reskimmed, with some bonding in places where needed, and the outside walls were repointed where the pointing looked bad. For the first few months we had a problem with an intermittent leak from the flat upstairs, but as far as I know it was rectified back in June. Anyway, since the heating has gone on in the last week, the paint on one section of the wall has started to peel off and we have efflourescence all the way up the wall just to the side of the radiator. It is concentrated mostly along the corner of the (external) door frame where the angle bead is. There are some 'rusty' marks on the angle bead too. I can't see any sign of a leak or any damp coming in from outside and the pointing and ground level render course are in good condition, there are no pipes running over the area, and I don't think the plastering has breeched the DPC. Is it possible this is just the old leak/new plaster finally drying out now the heating has been put on? Or should I be looking harder for a source of new moisture?
