Chris Plastow
Salt migration as you describe is the result of the evaporation of moisture that has been exposed to the soil, this may indicate rising dampness. Treatment may have been previously carried out without replacement of the render, this would also look like the condition you describe. The exterior ground level could be bridging the DPM, this would also seem the same. There are many things that can cause these conditions, get a specialist to look at it or give me more information
