Water seeping through a crack in a slab, basement wall, car park roof or lift pit? PU grouting seals the crack from inside with polyurethane resin, usually without hacking, and the job is typically done in 1 to 2 days.
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Noticing water seepage or dampness in your home? These are clear indicators that it’s time for re-waterproofing, whereby PU Grouting can be one of the solution for seepage in Singapore. Whether it’s visible cracks allowing water ingress or compromised concrete integrity, PU injection waterproofing offers a lasting fix to seal cracks and prevent potential structural damages effectively.
Polyurethane (PU) Grouting / Injection is a specialized technique that involves delivering PU resin into cracks or voids in concrete, creating an impermeable barrier that prevents water entry, and rapidly mitigates water infiltration. Popular in Singapore’s high-humidity environment, this method effectively seals off leaks by injecting PU resin into identified concrete cracks, which expands upon water interaction, ensuring a lasting waterproof defense.
Over time, buildings and structures settle into the ground, sometimes unevenly, causing stress and cracks in the concrete.
Applying more weight than the concrete was designed to bear can cause cracks due to overload.
During the curing process, concrete can shrink slightly, leading to the formation of hairline cracks.
The corrosion of steel bars embedded in concrete can expand and exert pressure on the surrounding concrete, causing it to crack.
The first step involves a thorough inspection to identify the source of leakage and the extent of the damage, crucial for PU grouting in Singapore.
Cleaning the area and removing debris/contaminants for proper PU adhesion.
Small ports installed along cracks for precise PU grout delivery.
PU resin (hydrophobic or hydrophilic) injected through ports.
Allowing time for resin curing/expansion to seal cracks, followed by integrity evaluation.
PU (polyurethane) grouting is a leak repair method where polyurethane resin is injected through small ports drilled along a crack in concrete or screed. The resin reacts with moisture and expands to fill the crack, voids, and capillaries, forming a flexible waterproof seal inside the structure. It is used in Singapore for slab seepage, basement walls, and lift pit leaks.
Polyurethane injection grouting stops leaks through three actions. The injected resin chases the water path inside the crack, reacts with water to expand 5 to 30 times its original volume, and cures into a flexible rubber-like seal. The result is a closed-cell foam barrier that blocks water while staying flexible enough to handle natural building movement and thermal expansion.
PU grouting is the right solution when water is leaking through cracks in a concrete slab, basement wall, lift pit, retaining wall, or floor screed, and traditional surface waterproofing cannot reach the source. It works best on active leaks where water is currently flowing, since the resin needs moisture to activate. PU grouting cannot fix dry-side surface waterproofing failures.
PU grouting uses water-reactive polyurethane resin to seal active water leaks; the cured material stays flexible and tolerates structural movement. Epoxy injection uses a rigid two-part epoxy that bonds cracks structurally, restoring concrete strength but offering no flexibility. Choose PU for waterproofing live leaks, epoxy for structural crack repair on dry concrete. They are not interchangeable.
A properly applied PU grouting repair lasts 10 to 20 years in Singapore conditions, depending on resin type and exposure. Hydrophobic PU resin (denser, water-reactive) lasts at the upper end. Hydrophilic PU resin can shrink in fully dry conditions and may need re-injection after 5 to 10 years. Lifespan also depends on whether the original crack cause has been addressed.
No. PU grouting is designed to seal cracks in concrete and screed, not to repair leaks inside metal water supply pipes. A burst or pinhole leak in a copper, stainless steel, or PVC pipe needs pipe replacement or epoxy pipe lining by a PUB-licensed plumber. PU grouting can only seal the surrounding concrete after the pipe itself has been fixed.
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