DPC is an acronym for Damp-Proof-Course. The main purpose of DPC waterproofing membrane is to prevent rising damp from entering load bearing walls that may cause weakening of structures, cracks in plaster and blistering of plaster or paint finishes on walls. There are currently non-SABS and SABS certified waterproofing membranes available and they are both made of low-density recycled polyethylene.
DPC comes in various thicknesses but currently the only SABS certified DPC has a thickness of at least 375 micron. DPC rolls are normally 40 meters long but lately they are also sold in 30 meter rolls. The standard widths that are available are 110mm, 150mm, 225mm, 300mm, 340mm, 400mm and 600mm wide (of which the 110mm is made for a single brick wall, the 150mm for a maxi-brick wall width and the 225mm for a double (cavity) brick wall. Specific mechanical properties and strengths of the DPC membranes are described in the SANS 952 specification. Apart from having a very low water vapour transmission rate (to prevent rising damp) the following properties are considered to be of vital importance for DPC membranes:
- It should have a high puncture resistance;
- It should have very good tensile properties (breaking strength and a high percentage elongination before it breaks);
- It should have a high resistance against accelerated aging.
SABS certified membranes will last and give the necessary protection to load-bearing walls for a lifetime provided that they are installed correctly and not damaged prior to and/or during the building process.