DAMP PROOFING SYSTEMS COMPARISON

About 50-60 years after the construction of a building the original Damp Proof Course (DPC) is likely to get damaged, for several reasons:

  • Normal aging of the materials
  • Corrosive effects of the ground salts
  • Frost and temperature fluctuations
  • Mechanical stress and vibrations
  • Micro-organisms, moulds and bacteria
  • Radioactive fallout

To reverse or fix the damage, several damp proofing systems have been developed. The table below summarises the most important points of the main damp proofing systems:

MECHANICAL SYSTEM ADVANTAGES
  • If done right, physical damp proof courses can last a long time and give full protection.
MECHANICAL SYSTEM DISADVANTAGES
  • Very noisy, labor intensive and costly.
  • Severely interferes with the structure of the building, high level of shocks and vibrations.
  • High risk of settlement cracks especially at the window or door frames as the masonry might skid on the metal plates.
  • Metal plates insertion is not suitable for certain types of houses such as stone masonry (the plates must be horizontal), houses on a hillside or for walls with lateral stress.
  • Corrosion: Ground salts can corrode some metal plates and changing the sheets thereafter can be a major problem.
CHEMICAL SYSTEM ADVANTAGES
  • Relatively cheap if only short wall sections have to be injected.
CHEMICAL SYSTEM DISADVANTAGES
  • Not suitable for old historical buildings where interfering with the building structure is prohibited.
  • Injecting stone walls can be problematic.
  • Relatively high failure rate in the long run.
  • Work intensive, requires messy building work.
  • The replastering masks the potential failure of the DPC, giving building owners a false peace of mind that the dampness problem has been fixed when it hasn’t.
  • Not a permanent solution long term to the dampness problem.
  • Does not offer a solution to the problem of existing dampness inside the walls. Walls can only dry out through the slow natural evaporation.
  • Damp walls degrade the thermal insulation of the building resulting in increased heating costs.
  • Invasive, non-reversible: the chemicals can’t be removed from the walls once injected.