WHAT IS DAMP PROOF COURSE ?

DAMP-PROOF COURSE


  • Damp-proof course is a horizontal barrier  in a wall to prevent moisture rising by capillary actions through the structure from the foundation. This phenomena is known as rising damp. A DPC layer is laid below the masonry walls, regardless, whether the wall is partition wall or load bearing wall.
  • The dampness creates unhygienic conditions in the building and also reduces the strength of structural components.
  • Provide a damp proof course between the source of dampness and the part of building adjacent to it. 
  • Damp proof course should cover the full width of wall. 
  • At the plinth level, DPC is provided in the building. Plain cement concrete is generally used for DPC at plinth level with thickness of minimum 25 mm and mix proportion of M15.

Other methods to prevent dampness are Damp-proof membrane, integral damp proofing,  surface suppressant coating, cavity wall construction and pressure grouting.

  • In the damp-proof membrane, Membrane material is applied to prevent moisture from ground. A common example of it is polyethylene sheeting laid in  the concrete slab to prevent slab engaging with dampness. A DPM may be used for the DPC.
  • In the integral damp proofing, Waterproofing compound is added to the concrete to improve its property to resist moisture. This compound makes concrete itself impervious.  
  • In the surface suppressant coating, A thin coat of waterproof chemical are applied on the top surface of concrete such as epoxy resin to resist non-pressurized moisture.
  • In the cavity wall construction, An internal walls are separated from the external wall. there would be cavity between them.
MATERIALS USED FOR DPC ARE :

  • Flexible materials like butyl rubber, hot bitumen (asphalt), plastic sheets, bituminous felts, sheets of lead, copper, etc.
  • Semi-rigid materials like mastic asphalt
  • Rigid materials, like impervious brick, stone, slate, cement mortar, or cement concrete painted with bitumen, etc.
  • Stones
  • Mortar with waterproofing compounds
  • Coarse sand layers under floors
  • Continuous plastic sheets under floors

PROPERTIES OF MATERIALS FOR DPC :
An effective damp proofing material should have the following properties;
1. It should be impervious.
2. It should be strong and durable, and should be capable of withstanding both dead as well as live loads without damage.
3. It should be dimensionally stable.
4. It should be free from deliquescent salts like sulphates, chlorides and nitrates.

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