Preliminary selection of exterior waterproofing systems 2021

Additional considerations

Waterproofing is subject to the environmental conditions of the site, applicable building codes, and the building conditions it is intended to protect. Typical site and building conditions for a specifier to consider are:

Site soil and water table

Ratings are generalized in nature. Qualified design or construction professionals must determine products to be used for specific products and applications

Will the ground have hydrostatic conditions? Will there be soil or groundwater conditions that are deleterious to waterproofing? How does the structure resist hydrostatic loading? Vapor barriers can be used in non-hydrostatic conditions to prevent water vapor migration from damaging impermeable floor finishes, but should not be used in hydrostatic conditions. Typically, hydrostatic grade waterproofing also functions as a vapor barrier.


Many projects require perimeter shoring, such as steel wide-flange soldier beams with treated wood lagging. Tiebacks or rakers used to resist loading from the adjacent soil may have to be removed during later stages of construction; this requires out-of-sequence patching of waterproofing and needs to be addressed.

Waterproofed surfaces

Each structural material has characteristics that affect waterproofing design. Shotcrete, for example, has a tendency for voids and slump to form during placement. The unique challenges of each substrate should be considered and mitigating measures specified.


Non-hydrostatic walls usually have drainage to a base-of-wall collection system that conveys water away to a sump or storm sewer. The drainage must be designed to accommodate expected site drainage in service. Misdirected surface water or unexpected ‘perched’ below-grade water can increase demand on drainage capacity. The waterproofing specifier may have to remind the design team of the need for adequate drainage for proper waterproofing performance.

Damage during construction

Waterproofing is generally installed early in a project schedule and may remain exposed for weeks or months. On horizontal surfaces, it may even be used as a work platform. consider means to protect and repair waterproofing until it is properly covered.

Post-construction repairs and supplemental waterproofing

grout injection can be used to repair leaks in below-grade concrete and to help conditions not easily waterproofed by other means. Crystalline coatings or slurries can be used to repair seepage and dampness on the ‘negative side’ of the structure, or as a supplement to waterproofing on the ‘positive’ side of the structure.


1a. Balcony – Split Slab 1b. Balcony – Traffic Bearing Coating1c. Balcony or Walkway – Thinset Tile 2a. Elevated Walkway – Split Slab 2b. Elevated Walkway – Traffic Bearing coating 3. Pedestal Pavers 4a. Planter – Primary Waterproofing 4b. Planter – Secondary Waterproofing 5. Concrete Paving 6a. Pool – Primary Waterproofing 6b. Pool – Secondary Waterproofing 7. Slab on Grade – Non-Hydrostatic 8. Mat Foundation – Hydrostatic 9a. Elevator Pit – Non-Hydrostatic 9b. Elevator Pit – Hydrostatic 10. Sump Pit 11. Spread Footing – Non-Hydrostatic, Backfilled 12. Backfilled Wall – Drained 13. Fire Water Tank 14. Shored Blind Side Wall – Hydrostatic 15. Basement “Lid” 16. Blind-Side Wall – Non-Hydrostatic 17. Vegetative Roof

Other factors affecting waterproofing are beyond the scope of the guide.

Once a broad category of product is selected, performance and product variables such as application thickness, availability of materials and labor, costs, warranty provisions, environmental factors, project limitations, and other factors must be considered to refine one’s options within the category. Moreover, the guide does not address damp-proofing, water repellents, or roofing—processes sometimes grouped inappropriately with waterproofing.

Guide users must read manufacturers’ literature, industry reference materials, and codes to evaluate proposed materials for a specific application. When necessary, advice should be obtained from trusted manufacturer representatives or qualified  consultants. Information from independent testing facilities should be considered and, if necessary, tests can be performed on a mock-up to demonstrate the effectiveness of a product in a particular application.

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