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.