To define the appropriate waterproofing strategy and type of system for a specific project, it is important to consider not only the ground conditions but also the project requirements of the owner. The functionality and future use, service life and the total cost of ownership should also be considered.

Degree of watertightness

The British standard BS 8102:2009 describes different levels of watertightness required for the end use of a structure.

Grade 1

Basic Utility


Some seepage and damp areas tolerable*

  • Underground car parks
  • Plant rooms
  • Workshops

* Dependent on use

Grade 2

Better utility


No water penetration. Ventilation may be required

  • Underground car parks
  • Storage areas
  • Workshops
  • Electrical plant rooms

Grade 3



No water penetration, totally dry environment

  • Ventilated residential units and offices
  • Restaurants and commercial areas
  • Leisure facilities

Additional Requirements (formerly Grade 4)

As Grade 3 plus: Consider internal environment required


  • Air conditioning
  • Ventilation
  • Radon and methane protection
  • Residential areas
  • Computer rooms
  • Archives
  • Special purpose facilities and areas

Service life / durability

The performance of each different waterproofing
technology can generally be positioned as follows:


Total cost of ownership

The total cost of ownership (TCO) includes all of the building costs for the entire service life of the structure, including the initial investment, the cost of any loss or damage to interior furnishings and goods etc. due to water ingress, the cost of any repair and maintenance, plus the cost of any downtime during any such works.