Dampness in building is when excess water molecule is on building which results to visible growth of mould and destruction or disturbance of wall surfaces and materials or it is the access and penetration of moisture content into building through its walls, floor, roof etc.
Causes of Dampness in building
Dampness in building is caused by the followings:
- Rain penetration: If the roof is not well constructed to take out water rain, it may lead to dampness on walls due to leakages down from roof to wall.
- Level of site: This is the higher external ground level around the property. That is when the building level is lower to the road and the surrounding environment.
- Waterlogged soil: Moisture in the soil can rise up into the building through capillary action and cause dampness in building.
- Climate condition: When hot humid air comes in contact with materials cooled by the airconditioning process, it causes condensation on the liquid water on the surfaces.
- Defective orientation of building: Indoor activities which releases moisture into the air like cooking, dishwashing, clothes washing, bathing etc.
- Moisture entrapped during construction: Poor quality works when water penetrate through walls can occur as a result of inadequately installed roof covering,improper treatment or covering of oversite concrete.
- Defective construction: Leak from bad slate/tile or cracked concrete gutter will increase build up of moisture in walls ,timber and plaster.
Effects of dampness in buildings
- It causes rotting of wood.
- It causes corrosion of metallic fixtures.
- It deteriorate electric installations.
- It deteriorate carpet & furniture’s.
- It causes spots on the floors and walls.
- It causes petting off and removal of plaster.
- It causes bleaching and blistering of paints.
- It causes efflorescence in bricks, tiles and stones
- It is dangerous for the health of occupants.
- It reduces the life of structures
- It promotes growth of termites
Also check: Building construction tools and their uses
Prevention of Dampness in building
- Introducing damp proof course during construction of foundation especially in waterlogged area.
- Using raft foundation mostly in waterlogged area.
- proper concrete mix ratio and fine aggregates which helps to make concrete impervious.
- Adequate concrete thickness.
- Using bitumen on concrete roof surfaces.
- Mixing waterproof cement with concrete.
- Using breathable paint.
- cavity wall construction This is shielding the main wall of the building by an outer skin wall leaving a cavity in between the two. The cavity prevents the moisture from travelling from the outer to the inner walls.