High-Pressure Polyurethane Injection Waterproofing NSW

Specialist PU injection for active concrete leaks u2014 basements, lift pits, retaining walls and carparks across NSW. Using Normet TamPur and Sika Injection systems.

What Is Polyurethane Injection Waterproofing?

Polyurethane (PU) injection waterproofing is a specialist technique for stopping active water ingress through cracks, construction joints, pile heads, and voids in concrete structures u2014 from inside the structure and without excavation. It is categorically different from surface membrane waterproofing: rather than coating the surface, PU injection delivers expanding resin directly into the water pathway within the concrete itself.

The fundamental mechanism of PU injection relies on the chemical reaction between the polyurethane resin and water. When a water-reactive PU resin contacts water within a crack or joint, it undergoes rapid expansion u2014 expanding to 20u201330 times its original volume depending on the product u2014 and cures into a closed-cell, flexible, hydrophobic foam that fills the void and permanently seals the water pathway. The presence of water in the crack is not a problem to be managed before injection u2014 it is the catalyst that makes the seal work.

This water-reactive expansion makes PU injection uniquely suited to situations where other waterproofing methods fail: actively flowing cracks in basement walls, leaking construction joints in occupied carparks, groundwater ingress in lift pits, and hydrostatic seepage through retaining walls. In all of these situations, applying a surface membrane is not possible u2014 the water would prevent adhesion. PU injection reaches the water at its source and seals it from inside the substrate.

There are two primary PU formulations used in building injection waterproofing:

Flexible (hydrophilic) PU foam u2014 water-reactive, fast-expanding, remains flexible after cure. Used for active crack injection in structures subject to minor ongoing movement. The flexibility allows the seal to accommodate small crack movements without re-fracturing. Normet TamPur 116 is our primary product in this category.
Semi-rigid PU resin u2014 slower-reacting, denser foam, semi-rigid after cure. Used where a more durable, less compressible seal is required u2014 larger voids, deep injection applications. Normet TamPur 220 is our primary product in this category.

Where PU Injection Is Used in NSW

Polyurethane injection is not a general-purpose waterproofing method u2014 it is specifically suited to structures where water ingress is occurring through discrete cracks or joints in concrete, and where surface membrane application is impractical or impossible. In NSW, the most common applications are:

Basement walls and floor slabs u2014 water ingress through shrinkage cracks, construction joints, and wall-slab junctions in residential and commercial basements. PU injection is the primary treatment for active leaks in basement walls before any cementitious or crystalline coating is applied over the surface.
Lift pits u2014 lift pits in Sydney’s high-density building stock frequently sit at or below the water table. Confined space entry is required, and injection must be completed without removing the structure from service. High-pressure PU injection is the only practical treatment for active lift pit leaks in occupied buildings.
Underground carparks u2014 construction joint failures and active cracks in carpark walls and floors are treated with PU injection, staged to minimise disruption to carpark operations. Injection can be completed in sections, with traffic management to allow occupied areas to continue in use.
Retaining walls u2014 retaining walls in NSW’s hilly coastal terrain are subject to sustained hydrostatic pressure from retained soil. PU injection into crack pathways stops water ingress without excavation and without removing the retained soil.
Swimming pools and water retention structures u2014 cracks in pool shells and water tanks are injected with flexible PU to restore watertightness without draining the structure.
Tunnels and civil infrastructure u2014 injection grouting for water ingress control in underground civil structures, using high-pressure injection equipment capable of reaching deep into the concrete body.

Our PU Injection Process u2014 Step by Step

Polyurethane injection requires specialist equipment, trained operators, and a methodical approach. Econyc’s injection process:

Water ingress mapping u2014 the affected structure is surveyed and all active ingress points are marked and photographed. Injection port locations are calculated based on crack geometry, crack depth, and expected resin travel distance. Ports are typically spaced at 150u2013300mm centres for hairline cracks, wider for larger cracks and joints.
Port installation u2014 injection ports (packers) are installed by drilling into the concrete at a 45-degree angle to intersect the crack at its mid-depth. Port diameter and length are selected based on the concrete thickness and crack geometry. All ports are mechanically anchored and pressure-tested before injection begins.
Water flushing u2014 ports are flushed with water to confirm communication with the crack pathway and to pre-wet the crack, ensuring the PU resin contacts water immediately on injection.
Resin injection u2014 PU resin (Normet TamPur 116 or 220, or Sika Injection-101 RC) is injected using a high-pressure, low-volume injection pump at controlled pressure. Injection proceeds from the lowest port, moving upward, until resin appears from the adjacent port. Each port is then capped and the process moves to the next port.
Cure monitoring u2014 the injected section is observed during the cure period (15u201330 minutes for reactive PU). If water continues to flow from an adjacent port during cure, additional injection is performed until the flow stops.
Surface sealing u2014 after injection and cure, port holes are sealed with hydraulic cement or polymer mortar. The crack face may be surface-sealed with cementitious or epoxy mortar where required.
Documentation u2014 a completion report is provided documenting port locations, products used, volumes injected, and the observed result at each port.

Products We Use u2014 Normet and Sika Injection Systems

Econyc uses injection resins from Normet and Sika u2014 two of the leading injection system manufacturers in the world. Our product selection is based on the specific crack geometry, water flow rate, and substrate conditions identified during the pre-injection survey.

Normet TamPur 116 u2014 our primary product for active crack injection. A single-component, water-reactive, flexible polyurethane foam that expands 20u201330 times on contact with water. TamPur 116 cures to a closed-cell, hydrophobic foam that remains flexible, accommodating minor structural movement. It is particularly suited to fine cracks and construction joint injection in basement walls and retaining structures. Normet’s TamPur range is used on major underground infrastructure projects across Australia including road and rail tunnels.

Normet TamPur 220 u2014 a slower-reacting, two-component PU system used where a denser, less compressible foam is required. TamPur 220 is used for larger void filling, curtain injection behind failing membranes, and applications where the water flow rate is too high for TamPur 116 to control.

Sika Injection-101 RC u2014 a single-component polyurethane injection resin from Sika’s specialist injection range. Used where a controlled expansion rate and flexibility are required for fine crack injection in concrete structures. Sika’s injection range is backed by local technical support and Australian-specific application data.

All injection work uses Normet’s high-pressure injection pumps and packer systems, maintained to manufacturer specification. Using the correct injection equipment u2014 not a garden-variety caulking gun u2014 is critical to achieving the resin penetration depth and distribution required for a lasting result.

Important: No Warranty on Injection Waterproofing

Econyc does not provide a workmanship warranty on polyurethane injection waterproofing work. This is industry-standard practice for injection waterproofing, and it is important that building owners and strata managers understand why.

Injection waterproofing is applied to pre-existing cracks and joints in structures that have already moved, settled, or degraded to the point of failure. The performance of an injection seal after cure depends entirely on factors that are outside the waterproofing contractor’s control:

Future structural movement u2014 if the structure continues to move after injection (seasonal thermal movement, ongoing settlement, nearby excavation or vibration), the sealed crack may re-open or new cracks may form adjacent to the injection site. A flexible PU foam seal can accommodate some movement, but it cannot prevent re-cracking if the structural movement exceeds the foam’s elongation capacity.
Groundwater level changes u2014 if groundwater levels rise significantly after injection (due to wet season, neighbouring excavation changing drainage patterns, or altered site conditions), the increased hydrostatic pressure may force water through paths adjacent to the injected section.
Substrate condition u2014 the bond between the injected resin and the crack walls depends on the substrate condition at the time of injection. Heavily carbonated, chemically contaminated, or extremely wet concrete may affect resin adhesion in ways that cannot be fully assessed before injection.
Crack geometry u2014 not all cracks have a simple, accessible geometry. Branching cracks, cracks with multiple planes, and cracks that widen significantly with depth may not be fully sealed by injection from the surface u2014 even with correct technique and product selection.

What Econyc does guarantee is that the correct product has been applied using the correct technique by a trained, licensed contractor. We provide a completion report documenting the work, and we stand behind the quality of our application. If resin does not appear from adjacent ports during injection u2014 indicating incomplete filling u2014 we continue injection until it does. We do not leave injection sites until the work has been completed to the required standard. However, the long-term performance of the seal in a dynamic substrate is not something any injection contractor can responsibly warrant.

Areas We Service

Econyc provides polyurethane injection waterproofing services across all of NSW, including Greater Sydney, Newcastle and the Hunter Region, Wollongong and the Illawarra, and the Central Coast. We service both residential and commercial clients and are experienced in confined space injection (lift pits, underground carparks) with all required safety documentation and equipment.

Frequently Asked Questions u2014 PU Injection NSW

How long does PU injection last?
nThis depends on the substrate stability and groundwater conditions. In stable structures with consistent groundwater levels, a correctly injected PU seal can remain effective indefinitely u2014 the foam does not degrade significantly over time in the absence of structural movement. In structures subject to ongoing settlement or seasonal groundwater variation, the seal may require monitoring and re-injection at affected locations over time. We advise on expected performance based on our assessment of the specific structure.

Will PU injection permanently stop my basement leak?
nPU injection will stop the active flow of water through the injected crack or joint at the time of treatment. Whether that specific location remains sealed long-term depends on whether the structure continues to move and whether groundwater conditions change. In many cases, PU injection provides a permanent or near-permanent solution. In structures with ongoing movement or very high groundwater pressure, it may be a medium-term solution that requires monitoring. We will give you an honest assessment of likely outcomes for your specific structure before you commit to the work.

Can PU injection be done while water is actively flowing?
nYes u2014 this is one of PU injection’s primary advantages. The water-reactive chemistry means that the presence of flowing water in the crack activates the cure rather than preventing it. For very high flow rates, a faster-reacting product or a two-stage process (hydraulic cement plug followed by PU injection) may be used. We assess the flow rate during the pre-injection survey and select the appropriate approach.

How is PU injection different from epoxy injection?
nPU injection is for active, wet cracks where stopping water ingress is the goal. The cured PU foam is flexible and does not restore structural strength to the cracked element. Epoxy injection is for dry or damp cracks where structural restoration is the goal u2014 the cured epoxy is rigid and bonds the crack back to near-original structural strength. The two methods are not interchangeable. Using epoxy in an actively wet crack will result in bond failure; using PU in a structural crack will stop the water but leave the element structurally compromised.

Do I need to vacate my basement during PU injection?
nFor standard basement crack injection, the space does not need to be fully vacated, but the immediate work area should be clear. The injection resins we use have low VOC emissions, and the work area is ventilated during the process. For lift pit injection, confined space entry procedures apply u2014 the lift must be taken out of service and the pit must be ventilated before access.

Ready to Get Started?

Contact Econyc today for a free site inspection and fixed-price quote. Licensed, insured, and fully compliant with Australian waterproofing standards.