Following are the precautions to be taken to prevent dampness in buildings before applying various techniques.

  1. The site should be located on high ground and well drained soil to protect the foundation from moisture
  2. All exposed walls should be of sufficient thickness to protect against rain (Minimum 30 cm,
  3. Good quality bricks free from defects should be used
  4. Good quality cement mortar (1:3) should be used to make sure pattern and perfect bond in the building
  5. Cornices and string courses should be provided to divert rain water away from the walls
  6. All exposed surfaces like tops of walls, composite walls etc should be covered with water proofing cement plaster
  7. Cavity walls are more reliable than concrete walls in holding moisture
  1. use of damp proof courses
  2. water proof or damp proof treatment
  3. Integral damp proofing treatment
  4. Cavity Walls or Sacred Walls
  5. Gunniting or Shot Concrete or Shotcrete
  6. pressure grouting or cementation

These are layers or membranes of waterproof materials such as bituminous felt, mastic asphalt, plastic sheets, cement concrete, mortar, metal sheets, stones, etc., which are applied to all places in a building structure where water penetration is suspected or suspected. it happens. The best location or position of DPC in case of building without basement is at plinth level or structures without plinth level, it should be placed at least 15 cm above ground level. Damp proof course is provided horizontally and vertically in floors, walls etc.

DPC above ground level
DPC above ground level

Surface treatment involves filling the pores of the material exposed to moisture by providing a thin film of water-repellent material on the surface (interior/exterior). External treatment is effective in preventing moisture.

Several surface treatments, such as pointing, plastering, painting, distempering, etc., are given to exposed surfaces and also to the interior surface. The most commonly used treatment to protect walls from moisture is a lime cement plaster (1:6) (1-cement, 6-lime) mix ratio. Surface treatments typically consist of sodium or potassium silicates acting as a water proofing agent. Alternate applications include aluminum or zinc sulfate, barium hydroxide and magnesium sulfate. Soft soap and also have alternative applications in alum, uni and unseed oil; Bitumen, bitumen, wax and fat; Resins and gums Waxes and fats are not suitable in the tropics because they melt with an increase in temperature

Integral treatment consists of the addition of certain compounds to concrete or mortar during the process of mixing, which when used in construction act as barriers to the penetration of moisture under various principles.

i) Compounds like Chalk, Talc, Fowler’s Earth etc. have mechanical action principle (i.e., they fill the pores present in concrete or mortar and make them dense and waterproof)

ii) Compact and water proof Compounds like sulphate, calcium chloride etc. work on chemical action principle (i.e.) they react chemically and fill the pores to act as water repellent.

iii) Compounds like soap, petroleum, oil fatty acid compounds like sodium ammonium etc work on repulsion principle, i.e. used in concrete as a mixture to react with it and become water resistant

A cavity wall consists of two parallel walls or leaves or masonry skins separated by a continuous air space or cavity. The provision of continuous cavity in the wall effectively prevents transmission or leakage of moisture from the outer walls or leaf to the inner wall or leaf. Cavity wall has the following advantages.

(i) Since there is no contact between the outer and inner walls of the cavity wall, the chances of moisture penetration are minimized.

(ii) The cavity wall prevents the transmission of heat through the wall.

(iii) The cavity wall provides good insulation against sound.

(iv) Reduces the disturbance of cavity wall upfluorescence.

(v) Cavity wall also provides benefits such as economy, better comfort and clean conditions in buildings

The cavity wall construction and DPC details for flat roofs are shown in the figure below.

Cavity wall construction to prevent moisture

The technique of gunning consists in forming an impermeable layer of rich cement mortar (1:3) or fine aggregate mixture for water proofing on exposed concrete surface or on pipes, cisterns etc. to resist the pressure of water. With this technique, an impervious layer of high compressive strength (600 to 700 kg/cm2) is obtained and therefore it is also very useful for repairing or repairing old concrete works.

A mixture of cement, sand and water under pressure into a structural component or in cracks, gaps or crevices in the ground. In general, this treatment is given to the foundation to avoid the penetration of moisture. This technique is also used to repair structures, strengthen the ground to improve bearing capacity, create water cut-offs to prevent leakage, etc.

Er. Mukesh Kumar

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Er. Mukesh Kumar is Editor in Chief and Co-Funder at ProCivilEngineer.com Civil Engineering Website. Mukesh Kumar is a Bachelor in Civil Engineering From MIT. He has work experience in Highway Construction, Bridge Construction, Railway Steel Girder work, Under box culvert construction, Retaining wall construction. He was a lecturer in a Engineering college for more than 6 years.