i have bought ex council ground floor flat in a converted house and the council must have concreted the ground floor throughout and my problem started with damp and white powder at about 8 inches above ground level also the plaster beading is showing rust marks coming through the walls, around both chimney breasts in lounge and bedroom so i tried to rectify by bitting external airbricks in to chimney breasts and then i was going to renew damp and new course of bricks along the entry of the terraced house as this is where the damp seems to be coming in or up and then i noticed that the damp course at the front end of the house could be as much as 18 inches below the internal concrete floors so was wondering what i could do about this, the house has steps at the front making the bay window concrete floor about 3ft above ground level and the back end seems ok with dpc 2 course from ground level, hope you can understand what i mean, thanks for your help, very basic diy er,