Basement water proofing

A brief overview of basement Water Proofing of wall and floors

water proofing a cellar with a cavity drain membrane
Cavity Drain Membrane with perimeter drainage

Repair of a structural waterproofing system: In existing properties basement water proofing is carried out from the inner wall surface.  Often using a Cavity Drain Membrane as the older wall/floor masonry may be in a weakened condition as it will not put additional load on the floor and wall structure, sometimes a combination of type A & C may be used.  Within its design limits, a cavity drain membrane will manage the failure of the buildings ability to resist groundwater penetration.  For instance, I have found in the Edinburgh new town area the cellars floors are often well-drained and have no water table issues.  This is due to their construction and the geology.  A Cavity Drain Membrane system is commonly used to control the water percolating down through the pavement and porous ground above the under-pavement cellar.

failed basement water proofing
failed modern basement 2m below ground

New construction sites have a different set of waterproofing problems compared with an existing building which has a history of resisting water.  In a new building, you are excavating underground (and into the unknown), and the new site has a lack of site water history.  This is why more investigation is needed.  This starts with a desk study followed by a site inspection.  The research helps in select materials and create a suitable specification, which needs to address any ground contamination due to past usage of the land, ground gases, i.e. Radon and potential flooding of the area due to location.

This is why a combination of Type A and B waterproofing system is preferred, this is applied to the new structure externally, or as part of the structure and both may require a suitable maintainable land drain installed to prevent water building up on the outside and finding a defect.  By combining these, you may create a tanked construction which is able to resist water penetration.

Notes:

basement water proofing coating work
Type A structural waterproofing

Type A:  This system relies on a coating/membrane being applied to the wall/floor to make the structure resistant to the passage of groundwater. A manageable land drain should be installed to prevent water from finding a defect in an external coating or membrane and diverted to a suitable soakaway.  Groundwater should not be discharged into a vested sewer.

basement water proof walls
Type B structural water proofing

Type B:  Is the best form of the three types as the (often waterproof concrete) wall/floor construction structure is built to resistant to groundwater penetration.

Type C:  Is formed out of a studded plastic membrane which manages the water entering the building. This is often used for repairing an area (this is not a tanking). It can be combined with a Type A or B to make them more repairable.

cavity drain membrane
Type C Cavity Drain Membrane
pump for basement water management
typical pump unit for type C

Groundwater should not be discharged into a vested sewer, but surface water can be.