Repair Systems — Basement Water Ingress
Hydrophilic polyurethane injection systems
Technical product reference for hydrophilic PU injection systems used to seal active water ingress through cracks, construction joints, and cold joints in basement walls and slabs on Australian Class 2 strata and commercial buildings. Covers product selection, injection equipment, gel vs foam behaviour, application sequence and substrate conditions.
What are hydrophilic PU injection systems?
Hydrophilic polyurethane injection resins are injected into actively leaking cracks, joints and voids in below-grade concrete. They react with the water present and expand into a flexible foam (free-foam expansion up to ~40×) that fills and seals the water pathway across the wall. Because they are water-activated, they are particularly suited to wet, actively-seeping defects — the defining basement water-ingress condition.
One-component resins (Sika Injection-107) are the first choice for most active cracks — no metering pump is needed. Two-component fast-foaming resins (Sika Injection-101 RC) are used for high-velocity flow that would wash out a 1C resin, as a temporary waterstop. Injection is not a structural repair and does not suit hairline cracks below 0.2 mm (use acrylic gel) — and the structural condition must be assessed first.
Product Reference
Individual products — one card each — scroll to view all
Sika Australia
Sika Injection-107
1-component hydrophilic PU foaming injection resin
Sika Injection-107 is a ready-to-use 1-component, polyurethane, slightly flexible foaming injection resin for permanent watertight sealing of cracks, voids and interstices in concrete. It reacts only in contact with water, expanding to a permanently flexible, elastic foam with free-foam volume expansion up to ~40× and no shrinkage after curing. Injected via a 1-component pump through drilled packers (typically 150–300 mm spacing). For active seeping cracks; for high-velocity flow use a 2C resin (101 RC). EN 1504-5. Confirm AS/NZS 4020 for potable-water tanks.
Sika Australia
Sika Injection-101 RC
2-component fast-foaming PU — temporary waterstopping
Sika Injection-101 RC is a low-viscosity, fast-foaming, solvent-free, 2-part water-reactive polyurethane injection resin that cures to a dense flexible foam with a fine cellular structure, for the TEMPORARY waterstopping of high water intrusions in cracks, joints and cavities in concrete, brickwork and natural stone. Free-foam expansion in contact with water up to ~40×. Its short reaction time resists washout in high-velocity flow. It is a temporary waterstop — follow with a permanent sealing resin or tanking. Requires a 2-component pump. Confirm EN 1504-5 status from the Sika AU PDS.
Master Builders Solutions
Master Builders MasterInject 1320 (hydrophilic PU)
1-component hydrophilic PU injection resin
Master Builders Solutions (the former BASF Construction Chemicals business) supplies a single-component hydrophilic PU injection resin — MasterInject 1320 — which reacts with water to form an impermeable flexible seal when injected into cracks in concrete. NOTE: the page listed 'MasterInject 1308'; the current product appears to be MasterInject 1320 — confirm the correct AU product, expansion ratio, EN 1504-5 status and specs with Master Builders Solutions Australia.
System Comparison
Hydrophilic PU injection — confirm all selections against the current manufacturer TDS before specifying.
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Disclaimer
This page provides general technical information only. Final product selection must be confirmed against the current manufacturer technical data sheet, project specification, substrate condition, and structural engineer advice where applicable. Basement and below-ground waterproofing involves hydrostatic pressure — confirm system selection with a qualified waterproofing consultant before specifying. Do not rely on this reference as a substitute for professional advice.
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