Waterproofing Systems

As the Bay Area’s trusted waterproofing partner for top general contractors, our expertise includes:

  • Below-Grade & Blindside Waterproofing

  • Podium Waterproofing

  • Traffic & Pedestrian Deck Coatings

  • Injections & Pedestal Pavers

Waterproofing protects structures from water intrusion under hydrostatic pressure, commonly used in foundation walls, slabs, plaza decks, planters, green roofs, and elevator pits.

The selection of a waterproofing system depends on its application:

  • Positive-Side Waterproofing: Applied directly to the exterior face exposed to water

  • Negative-Side Waterproofing: Installed on the interior side of the structure to resist moisture intrusion

  • Blind-Side Waterproofing: Placed against an adjacent structure or soil retention system before the new structural wall is built

Outdoor patio with wooden deck, white tables, and black chairs. Planters with greenery line the edges. Urban buildings and trees in the background under a clear sky.

Waterproofing & Coatings

  • Various building features rely on fluid-applied waterproofing, including:

    • Patio Decks

    • Fountains & Reflection Pools

    • Pedestrian & Traffic Areas

    • Restrooms & Utility Closets

    • Paver Systems

    While these coatings require minimal maintenance, they will eventually need reapplication or replacement. Given the complexities of waterproofing, our Service Representatives can guide you in selecting the best solution for your needs.

Construction site with concrete wall being assembled and worker in safety gear.

Below-Grade Waterproofing

  • For below-grade structures experiencing leaks—such as parking garages, basements, tunnels, and elevator pits—Alliance offers an advanced injection solution to eliminate water intrusion and restore compromised waterproofing systems. Contact us today for an evaluation and proposal.

  • Positive-side waterproofing is applied to the exterior of a structure during new construction or after removing the overburden on an existing building. This method is often the most effective, as water pressure helps reinforce its performance, and installation defects can be fully inspected. However, if leaks occur due to faulty installation or structural movement, repairs require excavation or the use of negative-side waterproofing techniques. When exterior access is not possible, blind-side or negative-side methods may be necessary.

  • Negative-side waterproofing is used in remedial applications when exterior access is not feasible, protecting only interior surfaces. It is more of a problem-solving solution than a preventive measure and is less effective than positive-side waterproofing due to potential structural movement and cracking. Additional applications may be required to seal new gaps over time. However, its ease of application makes it a practical choice when positive-side methods are not an option.

Construction site with white sheathing and green scissor lift

Blind-Side Waterproofing

  • Blind-side waterproofing is used in new construction when excavation is restricted by property lines or space constraints. It is also applied in split- or mud-slab horizontal installations to waterproof the underside of structural slabs. Typically, bentonite sheet layers, with or without a protective membrane, are installed dry and activate upon exposure to moisture from concrete, groundwater, or runoff. The expanding clay fills voids and cracks in the structure, but proper confinement through backfilling or lagging treatment is essential to prevent material loss into voids.

Flat rooftop with metallic structures and railing, clear sky background

Podium & Plaza Waterproofing

  • Modern buildings often feature landscaped basements and roofs, known as plazas or podiums. Whether used as habitable spaces or parking areas, selecting the right waterproofing system is crucial. Key considerations include deck and differential movement, drainage, waterproofing at expansion joints, outlet placement, landscaping, and protecting the space below the deck.

    1. High-density polyethylene (HDPE) profiled sheets, combined with permeable geocomposite drainage/irrigation layers, prevent groundwater infiltration and enhance waterproofing performance. These systems can work alongside primary waterproofing or independently to isolate structures from soil, relieving hydrostatic pressure by directing water to drainage systems.

    2. Two-coat, solvent-free liquid waterproofing solutions, based on polyurethane or synthetic rubber technology, can be spray or roller-applied. These coatings cure by absorbing moisture from the air, forming a flexible yet durable water barrier capable of accommodating minor structural movements.

    3. Hot-melt liquid bituminous rubber waterproofing, reinforced with interlaid membranes, provides seamless protection for green roofs and podium decks. This system is also effective in winter applications, as it can be applied at low temperatures.

Worker applying protective coating on a flat rooftop with a roller brush and bucket, overlooking a parking lot and office buildings.

Traffic & Pedestrian Coatings

  • Maintaining surfaces in pristine condition is essential. Protect concrete and plywood from traffic abrasion, freeze-thaw damage, and chloride-induced corrosion, which can compromise reinforcing steel. For elevated decks, coatings provide effective waterproofing for the space below.