Blindside Waterproofing

Blindside waterproofing is the technique used to waterproofing below grade structures, such as basements retaining walls or underground parking structures by applying waterproofing materials from the exterior side of the structure before backfilling or installing other site elements.

The term “blindside” refers to the fact that the waterproofing is installed without direct access to the exterior surface of the structure. In other words, the waterproofing is applied “blindly” before the structure is fully constructed or backfilled, making it inaccessible for inspection or repair after the concrete is installed.

Blindside waterproofing is typically used in situations where traditional water[roofing methods, such as surface applied membranes or coatings, are impractical or ineffective due to limited access or space constraints. It provides a proactive approach to preventing water infiltration by creating a continuous barrier on the exterior side of the below grade structure.

Common materials used in blindside are:

Pre-Applied Membranes:

 – Pre-applied waterproofing membranes are typically composed of bitumen, rubberized asphalt or other synthetic materials.

 – These membranes are manufactured with a self adhesive backing, heat bonded to the exterior surface of the structures foundation once concrete is placed.

 – They form a continuous barrier that adheres tightly to the substrate, providing excellent waterproofing protection when it is applied correctly.

Self Adhered Membranes:

 – Self adhered membranes are similar to pre-applied membranes but are designed to adhere directly to the substrate without the need of additional adhesives or heating.

 – These membranes often feature mechanical and or chemical bonding characteristics that adhere to the concrete foundation once the concrete is cast.

Bentonite Sheets:

 – Bentonite waterproofing sheets consist of sodium bentonite clay sandwiched between geo-textile or polymer sheets.

 – When hydrated, bentonite cal forms a self-sealing barrier that swells to fill voids and cracks, effectively preventing water penetration.

 – Bentonite sheets are typically applied by adhering them to the exterior surface of the structure, where they provide reliable waterproofing protection.

Liquid Applied Waterproofing Systems:

Liquid applied waterproofing systems consist of liquid coatings or membranes that are applied directly to the substate using different methods of post applied blindside waterproofing.

 – These systems are versatile and can be applied to irregular surfaces, penetrations and corners to create a seamless waterproofing barrier.

 – Liquid applied membranes involve elastomeric coatings, polyurethane membranes, acrylic membranes or poly-gel membranes which get injected once the walls are installed through pre-installed ports or post applied via drilled holes/injected.

 – Cementitious membranes are installed after the walls are up and are applied on the inside of the work or added to the concrete to ensure waterproofing is in place.

Each type of blindside waterproofing has its advantages and disadvantages and is deleted based on a lot of factors like substrate, site conditions, conventional concrete forming vs shot-crete, weather, scheduling and timing issues, and lastly warranty requirements. By choosing the appropriate material and installation method, blindside waterproofing can effectively protect below-grade structures from water infiltration and damage.