My house is built on split level. The back wall of the lowest floor is retaining the front garden etc. These brick retaining walls have been painted but are flaking off and lumps underneath the paint are widespread. When you scrape the lumps off they are powdery. There is also a damp odour.
Is there any way of sealing the bricks prior to repainting and is so what preparation would be needed. Somebody suggested PVA?
Any advice would be appreciated