Waterproofing systems for below ground structures are faced with stringent requirements regarding durability, exposure and stress conditions. Today, owners generally request a service life of buildings of 50 years or more and infrastructure of up to 120 years. Lack of watertightness can severely reduce the long-term durability of buildings and below-ground structures. This can badly affect its planned use as water ingress will result in physical attack and deterioration of the concrete and embedded steel.

Type of exposure and stress

Below ground structures can be subject to many different exposure conditions including:

  • Different levels of water exposure and pressure (e.g. damp soil, percolating water or water under hydrostatic pressure, and open water, variable water tables)
  • Aggressive ground water containing chemicals (commonly sulfates and chlorides in solution)
  • Unequal static forces (due to load, settlement, or uplift)
  • Dynamic forces (e.g. from settlement, seismic activity)
  • Temperature variations
  • Gases in the ground (e.g. Methane and Radon)
  • Aggressive biological influences (plant roots/growth, fungal or bacterial attack)

Exposure impact on below ground structures

These different types of exposure may adversely influence the use, watertightness and durability of a basement structure, resulting in a reduced service life of the entire structure.

Exposure Impact on structure
Water ingress Damage to structure, finishes, contents and the internal environment (condensation and mould growth etc.), loss of thermal insulation, corrosion of steel reinforcement
Aggressive chemicals Concrete damage (due to sulfate attack), corrosion of steel reinforcement (due to chloride attack)
Unequal static forces Structural cracking
Dynamic forces Structural cracking
Temperature variations Condensation, scaling or cracking of concrete
Gas penetration Gas penetration and exposure for occupants
Fungal/bacterial attack Damage to the waterproofing system, finishes or contents