Hi, I have noticed on the external wall of our conservatory (lower half of the wall is brick) that there is a white fluffy mould type growth but only on the mortar and only below the damp proof course. It has only affected a length of wall externally where a sofa was pushed up against the wall internally, we dont heat the conservatory all the time. I have moved the sofa further from the wall to allow it to breathe and there are two small patches of salty / water stain type marks on the internal plastered wall.
Can anyone tell me what this mould growth is, is it a serious problem and how it may be treated?
Many thanks