I will be getting the wall started on Monday it is a single block wall, it is a dividing wall between me and next door neighbour, their garden is approx 18 inches higher than our garden, so what i want to know is when the wall is finished and plastered both sides and the soil is replaced behind the wall will i need to put something on the wall to stop the dampness from the soil penetrating through the wall, the wall will eventually be painted.