Sunken rooms are those that are formed below the normal level of the house or building by design due to terrain or architectural needs.
This could be the lounge, dining room or storage.
Whereas these rooms are below normal levels of the building and the abutting ground is normally moist and this leads to wetness of the surrounding building materials like walls or concrete.
In the event that dampness occurs, as materials used to construct walls are permeable, the internal part that is plastered and painted shows some moss like or hairy substance that is called efflorescence.
The treatment to dampness or efflorescence in sunken rooms is by water proofing the internal part of the wall.
The method involves using materials that are waterproof to stop the wetness from coming into the room.
The wall is hacked to remove the plaster at the depth below normal level of the building.
the level could be say three hundred millimeters or one feet below and this is the part that is treated.
Once the plaster is removed the mortar joints are raked out and a strong paste of rich cement sand mixture is plastered back then after its dry, the waterproofing material is plastered on the hacked surface.
The process is repeated again the following day and the third day new plaster is done to the protected wall.
About one week and in the same period is needed for curing by rubbing or using a brush to wet the plaster continuously for the cement to achieve maximum strength.
Painting to the wall which is now efflorescence or dampness free is done to the wall.
This whole process should take at least three days forwaterproofing and one to two weeks for painting to be done.