Post
by Perry525 »
Sun May 24, 2009 5:46 pm
Is this wall exposed to bad weather?
Does the wind blown rain beat against this wall?
If it does, then the wall is probably cracked and the rain is getting under the concrete, which is then preventing it drying out.
Take a careful look at the wall, checking for cracks that run level with the ground.
Probably you have an old soft mortar built wall, soft to allow it to expand and contract and someone has used a cement based render that is too hard and brittle and cracks rather than expanding and contracting with the seasons.