Ground water is contaminated with salts (sulphates, nitrates, etc.,). These salts become concentrated in the plaster and masonry in the areas from which moisture is evaporating. The ingress of moisture can also dissolve salts already present in the structure. These salts are generally hygroscopic, i.e. they attract and absorb moisture from the atmosphere, with the result that on humid days, even though a damp course has been inserted damp patches can appear on the wall surface and may spoil decorations. In addition to the contamination of the plaster, the underlying masonry also contains residual salts.
The removal of the original plaster will remove the majority of the salts, but unless the wall is re-rendered using a waterproof rendering system, the salts contained in the masonry can migrate back and spoil newly decorated surfaces.
We have a team of experts that can re-plaster affected areas both professionally and efficiently.