We have an exteranl single bricked wall, which is part of our porch. we have already took off all the plaster board from the wall because of damp. can anyone tell me what is the best way to treat the damp. we seem to have a slate damp course on the exteritor of the wall, but who ever put the plasterboard on placed it down past ground level as there was a gap between the wall and the concrete floor. Could this be why the wall was so damp??