Dampness | Damp Proofing Construction - Ishwaranand

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Dampness | Damp Proofing Construction

Dampness
Damp Proofing Construction

  • Dampness indicates the entry of presence of moisture in building due to several causes such as rainwater penetration, a rise of groundwater, condensation in building, improper drainage & orientation, use of defective materials or bad workmanship. 
Dampness, Causes of Dampness, Effect of Dampness, Materials used for Damp Proofing, Methods of  Damp Proofing, Damp Proofing Construction,
  • The treatment given to prevent leakage of water from the roof is called water-proofing.
  • The treatment given to keep the walls, floors, and basement dry is called damp-proofing.

Causes of Dampness

  • Dampness rising through the foundation walls. Moisture from the wet ground may rise well above ground level on account of capillary action.
  • Splashing rainwater which rebounds after hitting the wall surface.
  • Penetration of rain-water within unprotected tops from walls,  parapets, compound walls, etc.
  • In the case of sloped roofs, rain-water may percolate through a defective roof covering.
  • On condensation, this moisture present in the atmosphere becomes deposited on the components of each building.
  • In the case of flat roofs, inadequate roof slopes, improper rain-water pipe connections and a defective junction between roof slab and parapet. 
  • Due to leakages in wet regions of a building which combine kitchen, bathroom, water closet, etc.
  • The leakages could be on account of the use of sub-standard plumbing fittings and fixtures as well as faulty execution of work and bad work­manship.

Dampness, Causes of Dampness, Effect of Dampness, Materials used for Damp Proofing, Methods of  Damp Proofing, Damp Proofing Construction,

Effect of Dampness

  • This causes efflorescence which may presently result in that disintegration about bricks, stones, tiles, etc.
  • It may result in softening and crumbling of plaster.
  • That may cause bleaching also flaking of paint include 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 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 in floors, walls, etc.
  • The provision of D.P.C in a basement is normally termed as 'tanking.’
Dampness, Causes of Dampness, Effect of Dampness, Materials used for Damp Proofing, Methods of  Damp Proofing, Damp Proofing Construction,

Integral damp-proofing

  • A dividend of certain water-proofing compounds by the concrete mix to improve its impermeability.
  • Such compounds are available in the market in powdered as well as liquid form.
  • The compounds made from clay, sand or lime (chalk, fuller’s earth, etc.) help to fill the voids in concrete and make it waterproof.

Surface treatment

  • Surface treatment consists of filling up the pores of the surfaces subjected to dampness.
  • The value of water repellent, metallic soaps so as calcium also aluminium oleates including stearates is much effective in protecting the building upon the 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 from a machine having arrangements for mixing materials including a compressor as 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
Dampness, Causes of Dampness, Effect of Dampness, Materials used for Damp Proofing, Methods of  Damp Proofing, Damp Proofing Construction,

Cavity wall Construction

  • This consists of shielding the main wall of the building by an outer skin wall leaving a cavity in between the two.
  • Each cavity prevents the moisture of 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 outer leaf and  thickness to 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 wall efficiently prevents this transmission of dampness above head the inner wall.
Dampness, Causes of Dampness, Effect of Dampness, Materials used for Damp Proofing, Methods of  Damp Proofing, Damp Proofing Construction,

Purposes or advantages

  • There is no contact between every two leaves except at the wall ties impervious material, there not a possibility of moisture moving from the outer leaf before the inner
  • Then a layer of air in the cavity being non-conductor of heat from external face to the internal one
  • This wall has a 25% greater insulating value than solid walls
  • They have good sound insulation property
  • They are economical.
Dampness, Causes of Dampness, Effect of Dampness, Materials used for Damp Proofing, Methods of  Damp Proofing, Damp Proofing Construction,

Materials used for Damp Proofing

  • Flexible material:- bitumen felts, plastic sheeting (Polythene sheet), etc.
  • Semi-rigid materials:- Materials like mastic asphalt or a combination of materials or layers.
  • Rigid materials: A materials same first-class bricks, stones, slates, cement concrete, etc.
  • Grout consist like cement slurry also acrylic-based ingredients polymers

A requirement of the ideal material 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.

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