Two very different approaches to basement waterproofing. Understand when tanking is the correct solution, when injection is appropriate, and why each method has its own risk profile.
When water enters a basement or below-grade structure in NSW, two fundamentally different remedial approaches are available: basement tanking and crack injection. These methods are not interchangeable. Each is designed for a specific type of water ingress and a specific substrate condition. Specifying the wrong method leads to failure, wasted cost, and continued water entry.
Basement tanking is the application of a continuous waterproofing membrane system to the internal or external face of a below-grade concrete or masonry structure. It creates a physical barrier that prevents water under hydrostatic pressure from penetrating the structure. External tanking applied to the outside face of the basement wall is the most robust long-term solution but requires excavation. Internal tanking applied to the inside face is the common remedial approach where excavation is not feasible.
Crack injection is the injection of a sealant material directly into cracks, voids, and cold joints in a concrete or masonry structure to seal the specific water pathway. It does not create a continuous membrane. It addresses discrete defects rather than the entire structure. It is appropriate where water is entering through identifiable cracks or joints rather than through diffuse porosity in the substrate.
Basement tanking is the correct approach where water is entering through multiple pathways distributed across a wall or floor surface, where the substrate is porous and water is seeping through the concrete matrix rather than through specific cracks, where hydrostatic pressure is high and injection sealants alone are insufficient to resist the pressure over time, and where a long-term durable solution is required for a basement being converted to habitable space.
Econyc’s basement tanking process involves thorough surface preparation including removal of all existing finishes, coatings, and contamination, application of a cementitious crystalline waterproofing slurry (Sika SikaTop 122 Plus or Tremco Dryflex) to the positive-side face where accessible, or a negative-side tanking system (Tremco TREMproof 50 or Sika Cem Gunite) to the interior face where external excavation is not feasible, full coverage of all walls, floor slab, and the critical junction between wall and floor, and flood testing before any interior finishes are applied.
The workmanship warranty on basement tanking systems is 7 years when installed by Econyc’s licensed contractors.
Crack injection is the correct approach where water is entering through discrete identifiable cracks, construction cold joints, tie holes, or pipe penetrations in an otherwise sound concrete structure, where the concrete substrate is dense and non-porous and the sole water pathway is the crack itself, where access for full tanking is restricted and the defects are localised, and as a first-line response to active leaks through specific cracks while a longer-term remediation plan is developed.
Econyc uses Normet injection products for crack injection in basement and below-grade structures. For active cracks with flowing or seeping water, Normet TamPur 116 is a water-reactive polyurethane foam that rapidly expands and cures on contact with water, sealing active ingress within minutes. For dormant cracks and cold joints in dry or damp conditions, Normet TamPur 220 is a low-viscosity polyurethane resin that penetrates fine crack geometries and cures to a flexible, permanently sealed joint. For structural cracks requiring rigid reinforcement of the concrete, Normet EpoResin low-viscosity epoxy is used to bond and rigidly seal the crack.
Crack injection does not carry a workmanship warranty in the same way as membrane systems. Injection seals a crack at a point in time. If the structure moves subsequently, or if there are additional cracks not identified and injected, water entry may recur through new pathways. This does not mean injection is inferior for the right application. It means the scope and limitations of injection must be clearly communicated and understood.
Many basement waterproofing jobs in NSW require both approaches in combination. A typical scenario: a concrete basement wall has distributed damp seepage through the substrate (requiring tanking) and also has three discrete cracks with active water ingress (requiring injection before tanking can proceed). In this case, the active cracks are injection-stopped first to arrest the active water entry, the surface is allowed to dry, and the tanking membrane is then applied over the prepared surface.
Another common scenario: a basement floor slab has a perimeter cold joint at the wall-floor junction that is leaking (requires injection or a combined injection-tanking treatment at the junction) while the floor surface is dry and sound (no tanking required). Here, crack injection at the cold joint combined with a flexible tanking treatment at the junction may resolve the issue without a full floor tanking application.
Econyc diagnoses each basement job individually. We do not apply a standard template. The method we specify is determined by the substrate condition, the nature of the water ingress, the access constraints, and the intended use of the basement space. You receive a written diagnosis and scope, not a verbal estimate.
Basement waterproofing demands products with high resistance to hydrostatic pressure, compatibility with concrete substrates, and long-term durability in a continuously damp environment. Econyc uses products from Normet, Sika, and Tremco that meet these requirements and carry full Australian technical documentation.
For injection: Normet TamPur 116 (water-reactive polyurethane foam, active leak stopping), Normet TamPur 220 (low-viscosity polyurethane resin, dormant and damp crack sealing), Normet EpoResin (low-viscosity epoxy, structural crack bonding). For tanking: Sika SikaTop 122 Plus (two-component flexible cementitious waterproofing slurry, positive side), Sika SikaDry (crystalline waterproofing compound for integral application to concrete mix or surface applied to hardened concrete), Tremco TREMproof 50 (negative-side crystalline waterproofing system for interior basement walls and floors), and Tremco Paraseal (bentonite sheet waterproofing for external excavated applications).
Econyc is transparent about the limitations of injection waterproofing. We do not offer a workmanship warranty on crack injection in the same way as for membrane systems, and we explain why at the time of quotation.
Crack injection seals a specific crack or pathway at a specific point in time using a reactive or flexible sealant. If the structure subsequently moves, develops new cracks adjacent to the injected zone, or if the injection material degrades under unusually aggressive chemical conditions, water may re-enter through a new pathway that was not present when the injection was carried out. This is a characteristic of injection technology, not a deficiency in Econyc’s workmanship.
This means that for basements being converted to habitable use, or for structures where long-term dry conditions are a strict requirement, tanking (with its 7-year workmanship warranty) is the more appropriate solution. Injection is best suited to infrastructure applications where ongoing maintenance is expected and accepted, active leak stoppage before a membrane system is installed, and non-habitable spaces where a degree of residual moisture is acceptable.
We will always tell you which approach is appropriate for your situation and why. We do not recommend injection as a cheap alternative to tanking when tanking is what the situation requires.
Can crack injection be used on a basement that has been converted to a bedroom?
We would not recommend crack injection as the sole waterproofing method for a habitable basement. In a habitable space, a continuous waterproofing system with a workmanship warranty is the appropriate solution. Crack injection may be used as part of the preparation for a tanking system but not as the sole barrier.
How long does crack injection last?
Polyurethane injection in a dormant (non-moving) crack with good penetration and cure can last the life of the structure. Injection into an actively moving crack may re-open as the crack cycles. Injection is a point-in-time repair and we do not guarantee its durability under unknown future structural movement.
How long does basement tanking last?
Properly specified and installed crystalline tanking systems have documented performance in structures of 20 to 50 years without replacement where the substrate remains structurally sound. Liquid-applied membranes have a shorter physical lifespan and may require inspection and topcoat reapplication at 10 to 15 year intervals depending on the product and conditions.
Is internal tanking as good as external tanking?
External tanking applied to the positive (wet) side of the structure is the superior solution because it prevents water from reaching the concrete at all, which slows reinforcement corrosion and structural deterioration. Internal (negative side) tanking resists water at the internal face but does not prevent the concrete itself from remaining saturated. For habitable conversions, a drainage channel and sump system may be recommended alongside internal tanking to manage the water that will continue to be held within the wall.
Contact Econyc today for a free site inspection and fixed-price quote. Licensed, insured, and fully compliant with Australian waterproofing standards.