Below-Grade Waterproofing

Blindside waterproofing is installed against shoring, lagging, shotcrete, or a substrate wall before structural concrete is placed. It is used where property lines or excavation support prevent later exterior access. Sheets, laps, tiebacks, penetrations, and concrete bond are inspected before reinforcement and concrete permanently conceal the system.

The design uses a smooth substrate, approved protection or bearing plates under chairs, controlled worker routes, clean storage, and repeated inspection during steel placement. Dropped bars, form stakes, welding debris, and equipment are kept off exposed membrane. Any puncture is repaired and inspected before the slab pour proceeds.

Options include PVC or rubber profiles, hydrophilic strips, metal waterstops, and injectable hose systems. Selection depends on joint movement, water pressure, concrete geometry, chemical exposure, and repair strategy. Harrowgate installs the engineered type at the exact location and secures it against displacement during concrete placement.

Often yes. Drainage reduces water load, controls perched water, and directs flow to approved outlets, while waterproofing protects when water reaches the structure or drains surcharge. The hydrogeotechnical and building design determines reliance on drainage. Harrowgate installs membrane, protection, drainage composite, collector pipe, and outlets as one coordinated assembly.

Visual inspection and material-yield checks are standard. Depending on membrane and specification, projects can add adhesion checks, flood testing, electronic integrity testing, vacuum chambers, or spark testing. The method must suit the system and substrate. Harrowgate repairs mapped defects and repeats the required verification before protection covers the area.

The existing membrane is exposed far enough to identify type, condition, and sound material. The consultant details compatible primers, transition sheet or liquid reinforcement, movement, and termination. If direct chemical compatibility is uncertain, a mechanical or designed transition is used rather than smearing incompatible materials across the joint.

Provide structural and waterproofing drawings, specifications, hydrogeological report, shoring and tiebacks, pour sequence, joint and waterstop schedule, penetrations, pits, sumps, protection, drainage, testing, access, and inspection requirements. Harrowgate builds a zone-by-zone quantity and tie-in plan so concealed phases are fully represented.