How to Fix Damp
In order to fix damp, firstly you must ascertain what type of damp you are dealing with, the extent of the problem and the cause or causes.
The cause is very important and the treatment can vary immensely depending on what has caused the damp. If the area is suffering from penetrating damp then fixing could be as simple as having a pipe leak repaired or a defective gutter in need of repair or maintenance.
Whereas dampness can also be caused by a lack of effective ventilation, this can cause condensation, which can result in the build-up of water droplets usually around windows and in corners of rooms.
This generally affects external walls as they are cooler and the treatment for this would be improve the ventilation, either by simply opening windows etc or in severe cases, you may need to have a ventilation system installed.
Remove moisture from the room
Once the new damp proof course is in place the walls are replastered using a rendering plaster which includes salt inhibitors and waterproofing agents to provide yet another level of protection . When complete, walls are skimmed to provide a smooth finish ready for the final stage of re-decoration to the wall after drying out.
Next: How can I tell the difference between condensation and rising damp.