PU Injection Waterproofing for Active Concrete Cracks
PU injection waterproofing in Malaysia for active concrete leaks. We seal basement, car porch, and structural wall cracks from RM80 per injection point.
When water is pushing through a live crack in a concrete slab, wall, or basement, a surface coating alone won't hold. Polyurethane (PU) injection grouting fills the crack from the inside under high pressure. The resin expands on contact with water, permanently sealing the path. It's the standard concrete crack repair for active leaks across Kuala Lumpur, Selangor, and the wider Klang Valley.
When Is PU Injection the Right Fix?
RLR Roofer is a Kuala Lumpur-based roofing and waterproofing contractor that has handled polyurethane injection (PU injection) repairs across the Klang Valley for over 10 years. Surface waterproofing works when the concrete is sound and dry. But when a crack is actively leaking, such as water dripping through a double-storey terrace car porch slab, seeping into a basement wall, or tracking through a condo deck, a topcoat will fail almost immediately. You can’t glue over running water.
PU injection grouting is the specialist concrete crack repair for exactly this situation. A polyurethane resin is pushed into the crack under pressure with a high-pressure injection pump, where it reacts with the moisture inside and expands into a flexible, permanent seal. The repair happens inside the concrete, not on top of it.
Common Applications Across the Klang Valley
PU injection waterproofing solves leaks on residential, commercial, and industrial properties across Kuala Lumpur, Petaling Jaya, Shah Alam, Kepong, and the wider Klang Valley in Selangor:
- Car porch slabs on terrace houses and bungalows leaking into the porch below.
- Basement walls and floors of condos and landed homes with groundwater seepage.
- Condo deck and balcony cracks dripping into the unit below.
- Retaining walls and structural walls with active moisture ingress.
- Flat concrete roofs on shoplots, factories, and industrial properties where a known crack is the water source.
Why PU Injection Waterproofing Beats Coatings
PU injection grouting addresses two things surface coatings can’t:
- Water pressure. The resin is injected under pressure with a professional grouting pump, pushing water out as it fills the crack.
- The full depth of the crack. The resin travels the entire width of the concrete, not just the visible face.
That’s why PU injection waterproofing is the standard specialist fix for active concrete leaks in Malaysia, and why RLR Roofer carries it as a dedicated service alongside our roof waterproofing across Kuala Lumpur and Selangor.
Honest Diagnosis Before We Inject
Not every leak needs PU injection. Sometimes a crack is dormant and a flexible surface membrane is enough. Sometimes the real leak is a plumbing pipe behind a wall, not the concrete itself. Our RM30 onsite inspection (2026 rate, waived when you approve the repair) identifies which is which, and whether PU injection is the right tool, the wrong tool, or one part of a combined repair plan. For typical budget expectations, see our breakdown of PU injection waterproofing cost in Malaysia.
How we deliver a real repair
Crack Mapping
We trace the active crack along the wall or slab, identify the best packer positions, and confirm the water path with moisture readings.
Packer Installation
Injection packers are drilled and fixed at staged intervals along the crack so the resin can be pushed along the entire leak path.
Resin Injection
PU resin is injected under pressure with a high-pressure grouting pump. The resin reacts with the moisture inside the crack, expanding and curing into a flexible, permanent seal.
Recent pu injection jobs
PU Injection FAQs
When is PU injection waterproofing the right fix?
PU injection waterproofing is the right fix when water is actively pushing through a concrete crack, especially in basements, car porches, structural walls, and flat slabs. Surface-applied waterproofing cannot stop live water pressure - PU injection grouting can, because the resin is forced in under pressure and expands on contact with water.
How long does a PU injection repair last?
A properly executed PU injection is typically permanent for the treated crack. If the surrounding concrete develops new cracks due to structural movement, those can be treated separately. We always explain whether injection alone is enough or whether it should be combined with surface waterproofing.
Does PU injection damage the concrete?
No. The drilled packer holes are small and are sealed after the job. PU injection is far less invasive than breaking out and re-pouring a slab, and it stops the water without opening up finishes or tiling.
Is PU injection better than hacking tiles for bathroom leaks?
For most upper-floor bathroom leaks, PU injection is the less invasive option because we can stop the leak from below the slab without breaking up tiles, screed, or sanitary ware. We use this approach whenever the leak path can be reached from the floor below. If the source is a corroded pipe or a failed full-floor waterproofing membrane, hacking is sometimes still the right call - we tell you which on the RM30 onsite inspection.
Do you offer a warranty on PU injection waterproofing in Malaysia?
Yes. Every PU injection job by RLR Roofer comes with a written workmanship warranty on the treated cracks. The warranty covers any recurrence of the original leak through the same crack path. New cracks that appear from fresh structural movement are not covered, which is standard practice for grouting work across the Klang Valley.
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