Layer of cement at base of house wall

I am presuming its a solid brick building no cavity sand and cement is to strong for the building it stops it breathing creating dampness, bricks are porous holding in water.

I would say you're sucking water/damp in somewhere, without seeing is difficult. Fix the ingress and then new render with a damp resistance ability and all should be good. Mark Mcleod

With out looking my guess would be to use lime mortar,this allows for a certain amount of movement

If the house as been damp proofed there should be no need for the cement base In fact if the house was originally built with a lime mortar mix then cement mortars should not be used as this can cause the face of the bricks to deteriate over a period of time