Two injection products, two very different performance profiles. Understanding when polyurethane foam is the right answer and when epoxy resin is required for crack repair in NSW.
When a concrete or masonry structure has a crack that is allowing water ingress, injection sealing is often the most practical remedial option. Two types of injection product dominate the NSW market for waterproofing applications: polyurethane (PU) injection systems and epoxy injection systems. Understanding the difference between them is essential for specifying the right product for each application.
Polyurethane injection products react with water and expand to fill cracks, voids, and pathways. They cure to a flexible, compressible foam or gel. They are particularly effective for stopping active leaks because the water present in the crack is part of the reaction mechanism. PU injection is primarily a waterproofing tool: it seals cracks against water ingress but does not restore the structural continuity of the concrete.
Epoxy injection systems consist of a low-viscosity two-part epoxy resin that is injected into dry or slightly damp cracks under pressure. Epoxy cures to a rigid material that bonds to the crack faces and restores the structural continuity of the concrete. Epoxy injection is primarily a structural repair tool that also creates a water seal. It does not perform well in wet or actively leaking cracks.
Polyurethane injection is the correct choice for the following situations: active or seeping cracks where water is present in the crack at the time of injection, expansion joints, control joints, and cold joints where ongoing movement is expected and flexibility in the injected material is required, cracks in tunnel linings, basement walls, and retaining walls under active hydrostatic pressure, and pre-treatment of active cracks before a membrane or tanking system is applied to the substrate surface.
Econyc uses Normet TamPur 116 for active leak injection. TamPur 116 is a single-component, hydrophilic polyurethane that reacts on contact with water. It foams and expands rapidly, filling the crack geometry and stopping water flow within minutes. The cured foam is flexible, allowing for minor crack movement without re-opening. TamPur 116 is approved for use in structures where the injected material may come into contact with potable water.
For cracks that are damp or periodically wet (not actively flowing), Normet TamPur 220 is the preferred product. TamPur 220 is a slower-reacting, lower-expansion polyurethane that penetrates finer crack geometries than TamPur 116 and cures to a more consistent, denser flexible material. It is appropriate for hairline cracks, cold joints in basement walls, and pipe penetration sealing.
Epoxy injection is the correct choice for the following situations: dormant (non-moving) structural cracks where restoring tensile and shear strength to the concrete cross-section is required, cracks in beams, columns, suspended slabs, and retaining wall stems where structural continuity must be maintained, cracks in areas subject to vibration or load-cycling where a rigid bond is required to prevent crack propagation, and pre-injection of structural cracks before topcoat or coating application on exposed concrete facades.
Econyc uses Normet EpoResin low-viscosity epoxy for structural crack injection. EpoResin has a viscosity suitable for penetrating cracks as fine as 0.1mm under controlled pressure. When cured, it achieves bond and compressive strengths that match or exceed the parent concrete, restoring the full structural capacity of the cracked section. EpoResin is a two-component system mixed at the injection port and cures in 24 to 48 hours depending on ambient temperature.
Epoxy injection is not a waterproofing solution for wet or actively leaking cracks. Epoxy will not bond to wet crack faces and will not stop active water flow. Attempting to inject epoxy into an actively leaking crack typically results in the epoxy being washed away before it cures. Where a crack is both structurally significant and actively leaking, the correct sequence is polyurethane injection first to stop the water, followed by epoxy injection once the crack is dry to restore structural integrity.
Both PU and epoxy injection follow the same general process, with differences in the preparation steps and timing requirements.
Econyc uses Normet injection products exclusively for crack injection waterproofing. Normet is a specialist manufacturer of injection systems for tunnels, infrastructure, and buildings with products designed specifically for the demanding conditions of below-grade and structural injection applications. Their products are used by major contractors on civil infrastructure projects across Australia.
Our injection product range includes Normet TamPur 116 (water-reactive PU foam, active leak control), Normet TamPur 220 (low-expansion PU resin, damp and dormant crack sealing), Normet TamGel 120 (acrylic gel for fine crack injection and rock consolidation), and Normet EpoResin low-viscosity epoxy (structural crack bonding and sealing). For specialist applications including tie-hole sealing, pipe penetration repair, and honeycomb voids in concrete, we also use Normet’s cementitious and hybrid injection materials.
We do not use generic injection resins or single-source imported products without documented Australian technical data. Every injection product we use has a current Australian technical data sheet and an appropriate approval for its intended application.
Econyc does not offer a standard workmanship warranty on crack injection in the same form as on membrane waterproofing systems, and we explain this clearly to every client before commencing injection work.
Crack injection seals the crack as it exists at the time of injection. If the structure subsequently moves, new cracks form adjacent to the injected zone, or the injection material is subjected to conditions outside its performance envelope, water entry may recur. This is not a failure of Econyc’s workmanship. It is the inherent limitation of injection technology: it treats a specific defect at a specific point in time and cannot anticipate future structural behaviour.
This means injection is not the appropriate primary waterproofing solution for habitable basement spaces, spaces with strict dryness requirements, or structures with ongoing movement or settlement. For these applications, a membrane or tanking system with a formal workmanship warranty is the appropriate specification. Econyc will always advise you when injection is and is not the right tool for your situation, and we will never recommend injection as a cost-saving alternative to a membrane system where a membrane system is what the situation requires.
Can PU injection be used to fix a crack in a swimming pool?
PU injection can be used to stop active water ingress through cracks in concrete swimming pool shells as part of a remediation programme. However, PU foam is not intended as a final finish in a pool environment and is typically followed by a full pool re-lining or membrane topcoat. Consult with us on the specific pool condition before assuming injection alone is sufficient.
Does epoxy injection restore the full strength of the concrete?
When correctly installed in a clean, dry crack, Normet EpoResin achieves bond strengths that match or exceed the tensile strength of the parent concrete. However, this assumes the crack is dormant and the crack faces are clean and dry at the time of injection. Injection into contaminated, wet, or actively moving cracks will not achieve full structural restoration.
How many ports are needed for a typical basement crack?
Spacing is determined by crack depth. For cracks in a 200mm thick wall, ports are typically spaced at 150mm to 200mm centres. A 1-metre crack in a 200mm wall typically requires 5 to 7 ports. For deeper structural elements such as retaining walls and raft slabs, spacing may be closer and secondary injection from the other face may be required.
What happens if injection does not stop the leak?
If injection does not fully stop a leak, we investigate and determine whether additional ports are required, whether the product selection was appropriate, or whether the leak is entering through a different pathway not addressed by the injection. We do not invoice for unsuccessful injection without offering a remediation path. In some cases, injection is not the appropriate method for the specific failure and we will advise accordingly.
Can injection be combined with tanking in the same job?
Yes, and this is frequently the correct approach. Active leaking cracks are injection-stopped first to arrest water flow and allow the substrate to dry. Once dry, a tanking membrane system is applied to the prepared surface. Injection and tanking address different aspects of the same waterproofing challenge and are complementary methods, not competing ones.
Contact Econyc today for a free site inspection and fixed-price quote. Licensed, insured, and fully compliant with Australian waterproofing standards.