White damp appearing at bottom of walls

To be honest without actually viewing the problem, and testing it with damp proofing equipment, I couldn't say. I have not known it to happen on any of the damp proofing I have carried out, but I am not saying it cannot happen. It needs the damp meter putting against the offending area to see if any damp is present. I hope this helps. Nick ANM Plasterers

A damp wall takes time to dry out. As a general guide, the drying rate is given as 1 month for every 25mm of wall thickness (BRE Digest 163, ‘Drying out buildings’). Thus 230mm will take approximately 9 months to dry. However, the drying processes depend on conditions, ventilation and the type of masonry, so drying may take considerably longer. During this period efflorescence (salting) can appear and should be wiped off regularly. Due to the potential prolonged drying of the wall, the following must be considered: 1. Delay any decoration for 4-6 weeks following replastering and allow for good natural ventilation to enhance drying. Do not apply heat or accelerated drying methods. 2. Do not use wallpaper for at least 12 months (longer on thick walls). 3. Redecorate using a non vinyl based emulsion. 4. Maintain good ventilation around walls. Note: The initial decorations should be regarded as temporary, the final decorations not taking place for at least 12 months after completion of the damp proofing and ancillary work. Of course this is just general information and I can't specifically state that this is what is happening here without seeing the offending area myself.