Chris Plastow
Slightly difficult to analyse from that info! Is it possible that the patches are quite round in shape? If so , this could be hygroscopic dampness caused by a repair or patch to the wall where the thickness of the plaster repair is absorbing moisture from the air. Scratch out a small hole in the plaster, down to the render, if it is more than 5mm thick, it is the problem and the patch must be removed and filled with render. If this is not the case, give me more information.
