• The treatment given to prevent leakage of water from the roof is called waterproofing.
• The treatment given to keep the walls, floors, and basement dry is called damp-proofing.

Causes of Dampness

• This causes efflorescence which may presently disintegrate bricks, stones, tiles, etc.
• It may result in softening and crumbling of plaster.
• That may cause bleaching also flaking of paint including the formation of coloured patches.
• It may lead to the corrosion of metals.
• It may damage electrical fittings.
• It promotes the growth of termites.
• It breeds mosquitoes and creates unhealthy living conditions for the occupants.

Methods of  Damp-Proofing

1. Membrane damp-proofing
2. Integral damp-proofing
3. Surface treatment
4. Guniting
5. Cavity wall construction

Membrane Damp-proofing

• This consists of providing la layer or membrane of water-repellent material between the source of dampness and the part of the structure adjacent to it.
• This type of layer is commonly known as a damp proof course (D.P.C.)
• It consists of materials like bituminous felts, mastic asphalt, silicon, polymers, plastic or polythene sheets, cement concrete, etc. 
• Depending upon the source of dampness, D.P.C. may be provided horizontally or vertically on floors, walls, etc.
• The provision of D.P.C in a basement is normally termed as ‘tanking.’

Integral damp-proofing

• Surface treatment consists of filling up the pores of the surfaces subjected to dampness.
• The value of water repellent, metallic soap calcium also aluminium oleates including stearates is much more effective in protecting the building from heavy rain.
• The bituminous solution, cement coating, transparent coatings, paints and varnishes fall are also used.
• Other surface treatments given to walls are lime cement plaster.
• The walls plastered with cement, lime, and sand mixed in proportions of 1:1:6 are found to serve the purpose of preventing dampness in the wall due to rain effectively.

Guniting

• This consists of depositing an impervious layer of rich cement mortar over the surface to be water-proofed.
• The operation is carried out by the use of a machine known as a cement gun.
• Each assembly broadly consists of a machine having arrangements for mixing materials including a compressor forcing the mixture below pressure within a 50 mm dia flexible tube pipe.
• The hose a pipe has a nozzle at its free end to which water is supplied under pressure through a separate connection

Cavity wall construction

• This consists of shielding the main wall of the building with an outer skin wall leaving a cavity in between the two.
• Each cavity prevents moisture from travelling from the external to the inner wall.
• That consists of two walls with a 5 cm to 8 cm cavity within them
• The outer wall is also known as the outer leaf and  thickness of 10 cm (half brick)
• Some inner wall is sufficiently thick also strong to carry  those imposed load safely
• The minimum thickness of the inner wall is 10 cm (half brick)
• The provision of a continuous cavity in such wa efficiently prevents this transmission of dampness above the and the inner wall.

Materials used for Damp Proofing

• It should be impervious.
• It should be strong and durable.
• It Should be capable of withstanding both dead as well as live loads without damage.
• It should be dimensionally stable.