Typically used in basements, in-ground storage tanks and retaining walls, negative-side waterproofing is generally applied as a remedial fix or as a preventative waterproofing system where its’ not practical to apply remedial waterproofing to the external, or ‘positive’ surface of the structure.  The typical stages of a negative-side waterproofing treatment include an improvement to the substrate to increase the watertightness and a hydrostatic coating as a last defence to hold back water from entering the space.

There are several waterproofing products on the market which allow negative-side waterproofing to be both viable and cost effective.  The products allow for aspects such as pressure from water that may enter from the positive side, ensured bonding with the building materials (even when water is present) and endure any natural movement as well as the expansion and contraction of the structure.  Typical categories of negative-side waterproofing materials include:

• Penetrating liquid acrylic waterproofing materials consisting of expanding polymer or crystalline additives which expand to seal voids, cracks and crevasses where water seeps in.
• Cementitious surface coatings or epoxy injections which are pushed into water pathways and when the product hardens a barrier is created.