Wall repair after water damage can cost a tremendous amount. As well as the obvious damage, there will be underlying damage to any wooden foundations and insulation. Roofing issues can cause wall damage, as well as flooding or bad guttering.
1 - Dry Wall Repair
It is not always possible to repair dry wall. The damage can be irreversible and the dry wall will need total replacing. Sever damage can also affect the insulation and sidings of the wall. Outside damage, caused by bad guttering or roofing, will inevitably end up with water cascading down the same part of a wall, causing long term damage.
2 - Gypsum Plaster
Gypsum plaster is not good at withstanding damp conditions. It is a rather weak type of plaster which can be removed quite simply. If the damp in your home has been affecting walls and has come through to the inside, it may help to rent an industrial dehumidifier to extract the excess water before attempting repairs.
3 - Brickwork
For homes where the bottom half is brick work and the top is plaster, the excess water must be extracted. Once dried out, the wall can be repaired if the plaster is replaced. Check the pointing on the brickwork and make sure the cement is still good throughout.