Stop Active Leaks Without Excavating the Structure
Injection waterproofing stops water entering an existing concrete structure by injecting a sealing material into the crack, joint or failed waterproofing layer from inside the building. In high-rise and mid-rise condominiums, rental towers, office buildings and commercial properties, it is often the only practical way to repair leaking parking structures, podium decks, foundation walls and elevator pits. The alternative is excavation, removing a traffic deck or landscaping, or taking occupied space out of service.
Nusite Group has delivered commercial waterproofing systems across the GTA and Southern Ontario since 1990. Our crews self-perform injection scopes using polyurethane, epoxy, curtain grouting and GTI-1000 polymer gel systems, selected to suit the structure, the water condition and the movement the repair must accommodate.
Discuss Your Injection Waterproofing Project
Water intrusion in an existing condominium, office or commercial structure does not always mean excavation, membrane replacement or closing space. Where access is limited or excavation would be disruptive, injection waterproofing may provide the repair.
Nusite Group can review the existing conditions, identify the source of the water intrusion and recommend the injection system, or other commercial waterproofing system, suited to the structure.
When Injection Is the Right Repair
Injection is a remedial system for existing structures. It is most effective where:
- Water is actively entering through cracks, joints, penetrations or a failed waterproofing membrane
- The exterior face of the structure cannot be reached without excavation, shoring or work on an adjacent property
- What sits above or beside the failure, such as a traffic-bearing deck, pavers and landscaping, or an operating elevator, has to stay in place
- The building is occupied by residents or tenants, or is revenue-generating, and the repair must be phased around operations
Injection is not the right repair for every leak. Widespread membrane failure across a deck, deteriorated concrete that needs structural rehabilitation, or a defect that requires engineering review may call for a different system, such as exterior waterproofing or full membrane replacement. Every scope starts with an assessment of the water entry, the structure and the existing waterproofing assembly.
Injection Waterproofing Methods
The injection material determines how the repair behaves once it is in place. We select from four systems.
Polyurethane Leak Injection
For actively leaking cracks and joints. Polyurethane resin reacts with water and remains flexible after curing, so the seal moves with the structure rather than fracturing.
Structural Epoxy Crack Injection
For dry structural cracks in slabs, walls and beams. Epoxy cures to a rigid, high-strength bond that restores the integrity of load-bearing concrete.
Curtain Grouting
For water entering through below-grade walls where there is no exterior access. Grout is injected through the wall into the soil or substrate on the positive side, forming a continuous barrier behind the structure. Materials include polyurethane, acrylic gel, silicate and cementitious grouts.
GTI-1000 No-Excavation Injection
For failed membranes beneath decks, slabs and walls. A non-curing polymer rubber gel is injected to the membrane plane, travels laterally along it, and re-establishes waterproofing continuity without opening the surface above.
Choosing an Injection System
The leak condition, the water present and the movement in the structure decide the system.
| Condition | System | Why |
|---|---|---|
| Dry structural crack in a slab, wall or beam | Structural epoxy | Rigid bond restores strength; not suited to active water |
| Active leak through a crack or joint subject to movement | Polyurethane | Reacts with water and stays flexible |
| Water entering a below-grade wall with no exterior access | Curtain grouting | Builds a barrier on the positive side of the wall |
| Failed membrane beneath a deck, podium or slab | GTI-1000 polymer gel | Travels along the membrane plane and stays flexible |
| Leak around a pipe or service penetration | Polyurethane or GTI-1000 | Depends on water volume and access |
Some conditions call for more than one system, such as a polyurethane pre-fill of large voids before gel injection. That decision is made during the assessment.
Injection Waterproofing Applications
Injection scopes are defined by the structure. Each condition below has its own failure pattern and its own operational constraints.
- Underground parking structures. Garages beneath condominium, rental and office towers, with leaks at construction joints, expansion joints, column bases and slab cracks repaired from below while levels are isolated and returned to service progressively.
- Plaza and podium decks. Membrane failures beneath pavers, soil, planters and residential amenity terraces, addressed from below without removing the overburden.
- Foundation walls and below-grade slabs. Including zero lot line walls built against shoring or an adjacent property, where conventional foundation waterproofing cannot be reached from outside.
- Elevator pits. Active leaks at the wall-to-floor joint, pit walls and service penetrations, scheduled with the building operator and the licensed elevator contractor.
- Construction joints, expansion joints and penetrations. Joints subject to building movement, and pipe or service penetrations where water concentrates.
- Tunnels and infrastructure. Leakage at segment, precast and construction joints under sustained hydrostatic pressure, combined with continuous movement and vibration.
Injection Waterproofing for High-Rise, Mid-Rise and Office Buildings
Most of our injection work is carried out on multi-storey buildings with occupied space above and parking below. The structures repeat from building to building; the constraints depend on who occupies them.
- High-rise and mid-rise condominiums. Leaks in underground parking garages, podium amenity decks, elevator pits and below-grade walls, often identified in an engineering condition assessment or reserve fund study. Work is coordinated with the property manager and condominium board, with notice to residents and phased access to parking levels and amenity areas.
- Rental apartment towers. Remedial injection in garages, storage levels and mechanical rooms below tenanted floors, scheduled to keep parking and building services available.
- Office buildings. Leaks in below-grade parking, loading areas, mechanical and electrical rooms and plaza entrances, phased around tenant operations and coordinated with facility management.
- Commercial, institutional and industrial buildings. Retail centres, hospitals, schools and industrial facilities where operations cannot stop for excavation.
More on our work in multi-storey buildings: High and Mid Rise Waterproofing
The Injection Process
Injection is a controlled, sequenced operation. Execution quality determines whether the repair holds.
- Assessment. We identify the water entry, the existing waterproofing assembly, the substrate condition and the movement in the structure, then select the system.
- Layout. Injection ports are planned against the crack, joint or leak pattern.
- Drilling and packers. Ports are drilled to the required depth and injection packers are set to control flow and pressure.
- Injection. Material is injected at controlled pressure and progressed through the treatment area until coverage is confirmed, typically by material emerging at adjacent ports.
- Sealing. Ports are withdrawn and the holes are sealed.
- Verification. The treated area is monitored and any residual seepage is addressed.
Built for Southern Ontario Conditions
Two conditions drive most below-grade waterproofing failures in the GTA. Road salt tracked into parking structures each winter creates a sustained chloride environment that degrades many repair materials and drives reinforcement corrosion, with water damage to finishes, equipment and vehicles on the levels below. Freeze-thaw cycling, thermal movement and traffic loading then apply repeated strain at the joints and cracks a repair has to seal.
Material selection is therefore as important as installation. A rigid repair at a moving joint will crack again; a flexible system matched to the movement will not. GTI-1000, for example, is tested under sodium chloride exposure at under 1% weight change (KS F 4935, manufacturer data).
Assessment, Pre-Construction and Budget Planning
We assess water intrusion conditions for owners, property managers and consultants, recommend an injection system, and help develop realistic budgets and phasing before work begins. Where a consultant has specified the repair, we work to the specification and coordinate sequencing with the project team.
Our Clients Are
- Construction Managers
- Project Managers
- Property Managers
- Asset Owners
- Condominium Corporations
- Cooperatives
- Government and ICI
- Architects
- Consulting Engineers
- Manufacturers
Why Project Teams Choose Nusite Group for Injection Waterproofing
Injection work is only as reliable as the crew executing it. Project teams rely on Nusite Group as their commercial waterproofing contractor for:
- Established experience since 1990
- Fully bonded operations, licensed across Ontario
- Up to $10 million in liability coverage
- In-house rotor/stator injection pump equipment for hot-applied gel systems
- Injection scopes self-performed by Nusite crews, not brokered to a third party
- Material and labour warranties, with coverage varying by system and scope
- Coordination within large construction teams
Serving the GTA and Southern Ontario.
FAQ
What is injection waterproofing?
Injection waterproofing stops water entering a concrete structure by injecting a sealing material (epoxy, polyurethane, grout or polymer gel) into a crack, joint or failed waterproofing layer through drilled ports. It is installed from inside the structure, so the exterior does not need to be excavated.
How does injection repair wall cracks and leaks?
Ports are drilled along or into the leak path and the material is injected under controlled pressure until it fills the crack or reaches the waterproofing layer behind it. Depending on the system, it seals the crack itself, forms a barrier on the positive side of the wall, or restores continuity across a failed membrane.
Can a leak be repaired from inside a commercial building?
In many cases, yes. Interior leak repair is the main reason injection is used on parking structures, podium decks, zero lot line walls and elevator pits, where reaching the exterior face would mean excavation or removing what sits above the failure. Whether it suits a specific leak depends on the structure and the extent of the failure.
Is injection waterproofing used on condominium and office buildings?
Yes. High-rise and mid-rise condominiums, rental towers and office buildings are where injection is most often used, because their parking garages, podium decks and elevator pits sit beneath occupied space that cannot be excavated or closed for long. Work is coordinated with the property manager, condominium board or facility team and phased around residents and tenants.
What is the difference between epoxy and polyurethane injection?
Epoxy cures rigid and restores structural strength, so it is used on dry structural cracks. Polyurethane reacts with water and stays flexible, so it is used to seal actively leaking cracks and joints that continue to move.
Does injection work on active leaks?
Yes, with the right material. Polyurethane, curtain grouts and GTI-1000 polymer gel are designed for wet conditions and active water. Epoxy is not, and is reserved for dry cracks.
How long does injection waterproofing last?
Service life depends on the material, the movement in the structure and the water exposure. Matching a flexible system to moving joints and cracks is what prevents a repair from failing early. Our injection work carries material and labour warranties, with coverage varying by system and scope.
Can the building stay in service during injection work?
Generally, yes. Work is carried out from inside the structure in defined areas, so parking levels, amenity spaces and occupied floors can be phased rather than closed. Elevator pit work may require the elevator to be taken out of service while the pit is accessed.
What areas do you serve?
We serve the Greater Toronto Area and Southern Ontario on commercial, institutional and industrial injection waterproofing projects.
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