PU injection waterproofing in Malaysia — how polyurethane grouting seals leaking slabs, tanks and basements from inside, what it costs and a flat-rate quote from a Klang Valley contractor.
PU injection is the fastest-growing leak-repair search in Malaysia, and for good reason: it fixes an active leak from inside the concrete, without hacking a single tile. A technician drills small ports into the leaking slab or wall, seats injection packers into them, and pumps liquid polyurethane (PU) resin in under high pressure. The resin follows the water paths inside the concrete, reacts with the water, expands into a dense foam and seals the leak shut. Because everything happens from the accessible side — usually the ceiling below a leaking bathroom — the floor upstairs stays untouched. That is what makes it the go-to repair for condo ceiling leaks, where hacking a neighbour’s bathroom is slow, political and expensive, and for structures you simply cannot open up, like water tanks, lift pits and basements.
Water never passes through sound, solid concrete — it travels through hairline cracks, honeycombs (air pockets left during casting), cold joints between concrete pours, and gaps around pipe penetrations. PU injection works because the resin is pumped in at pressures far higher than the water pressure, so it chases down exactly the same paths the water has been using. The clever part is the chemistry: polyurethane resin is water-reactive. The moment it meets the moisture inside the crack it starts to foam, expanding to many times its liquid volume and packing the void tight. Within minutes it cures into a semi-flexible, closed-cell seal that stays bonded to the concrete and tolerates the slab’s normal thermal movement. The leak’s own water is the trigger that sets the seal — which is why PU is the one repair that actually prefers a wet crack.
The same method is sold under several names, which confuses a lot of owners comparing quotes. The table below untangles the vocabulary before you compare prices.
| Term | What it means | Where you hear it |
|---|---|---|
| PU injection | The everyday name — injecting PU resin into concrete to stop leaks | Homes, ceilings, walls |
| PU grouting / pressure grouting | The same method; the term used on civil and M&E jobs | Water tanks, lift pits, basements |
| Polyurethane grout injection | The formal specification name for the same works | Tender documents, QS bills |
| Tile grouting / regrouting | A different job entirely — renewing the cement lines between tiles | Cosmetic bathroom refresh |
The only real trap is the last row: tile regrouting has nothing to do with pressure injection and is not waterproofing at all. If a quote for your leak says “grouting”, make sure you know which one you are buying — our grouting vs waterproofing guide untangles the three jobs that share the word.
PU injection is at its best where water is seeping through concrete under modest pressure and the structure itself is sound. The table shows the typical applications and how well the method suits each.
| Situation | Suitability | Notes |
|---|---|---|
| Slab seepage / dripping ceiling | Excellent | Sealed from below; the floor upstairs stays untouched |
| Cold joints & construction joints | Excellent | The classic water path in RC structures |
| Hairline cracks with active water | Excellent | The resin needs that moisture to react |
| RC water tanks | Good | PU grouting at RM120–RM300/point market rates |
| Lift pits & basements | Good | Often the only practical fix from the negative side |
| Honeycomb / porous concrete patches | Good | May need several passes to fill fully |
For the classic condo scenario — a stained, dripping ceiling under the upstairs bathroom — this is exactly the method behind our flat-rate PU injection ceiling leak service (RM650 per bathroom ceiling), and the wider upstairs-downstairs problem is covered in our inter-floor leakage guide.
An honest contractor will also tell you where PU injection is the wrong tool. It cannot fix a leaking or burst pipe: resin cannot seal against a pressurised water line, and injecting around one just hides the evidence for a few weeks — the plumbing must be repaired first, which is why proper diagnosis (isolating pipe leaks from slab seepage) comes before any drilling. It is also the wrong primary repair for structural cracks that are still moving or carrying load — those need assessment and often epoxy injection, which bonds the concrete back together rather than just sealing water out. And when a bathroom’s membrane has failed across the whole floor, injection can end up chasing leak after leak while the real fix is a new membrane — our injection vs membrane guide covers how to make that call. A contractor who injects everything is selling, not diagnosing.
This is not a caulking-gun job. A proper crew runs a high-pressure injection pump — electric or pneumatic, typically operating at 2,000–3,000 psi and above — feeding resin through mechanical packers: threaded metal ports, usually 10–13 mm, seated into holes drilled at an angle to intersect the water path inside the slab. Resin selection matters too: hydrophobic PU foams aggressively for fast waterstopping in actively flowing leaks, while hydrophilic PU cures more flexible and gel-like, suiting damp joints that move. Cheap DIY injection kits fail for exactly this reason — hand-gun pressure pushes resin a few millimetres in, when the leak path may run half a metre through the slab. The pump pressure, packer placement and resin choice are most of the skill you are actually paying for.
A typical bathroom-ceiling injection runs like this. First the crew traces the leak and rules out plumbing — dripping that slows when the upstairs bathroom is not used points to seepage, not a pipe. Next they drill injection holes at roughly 45 degrees, spaced along the stain or crack line so each hole intersects the water path inside the slab, and seat the packers. Injection starts at the lowest or wettest point: resin is pumped until it back-flows from the crack or from the next packer — the sign that the path is full — then the crew moves along the line. The foam expands and cures within minutes. Finally the packers come out, the holes are patched flush and the area is checked again once the upstairs bathroom goes back into normal use. Most single-ceiling jobs are done in two to four hours, and the room is usable the same day.
Correctly diagnosed and properly injected, PU seals routinely last five to ten years and often the life of the structure — cured polyurethane does not dissolve in water or shrink with age. What can shorten that is the building, not the resin: fresh cracks from settlement or thermal movement can open new water paths beside the sealed one, and a wholesale-failed membrane above will keep feeding water to new spots. That is why the warranty matters more than the brochure. ClickBina backs ceiling injection with a 6-Month No-Leak Warranty, and our waterproofing warranty guide explains what a meaningful warranty should actually cover — and which warranty wordings are marketing.
Most of the market prices PU injection per injection point at RM80–RM250 per point (indicative 2026, Klang Valley) — which sounds cheap until the point count lands after drilling has already started.
| Pricing model | Typical figure | Note |
|---|---|---|
| Market per-point rate | RM80 – RM250 / point | Point count is decided on site, by the contractor |
| Typical ceiling at per-point | 8–12 points → RM960 – RM3,000 | The RM80 headline rarely survives the count |
| ClickBina flat rate | RM650 per bathroom ceiling | Points unlimited, 6-Month No-Leak Warranty |
The per-point maths, the pricing games and the honest flat-vs-point comparison get a full breakdown in our PU injection cost guide, and the wider repair landscape sits in our waterproofing cost guide.
Injection and re-waterproofing solve different depths of the same problem. Injection seals the specific paths water is using right now — fast, tile-safe, RM650 for a ceiling. Re-waterproofing means hacking the upstairs floor, laying a new membrane at RM6–RM18 per sq ft, and retiling — a multi-day job costing thousands, but the right call when the membrane has failed wholesale. A useful rule of thumb: localised stains and drips point to injection; a floor that leaks along multiple walls and rooms points to the membrane. Our injection vs membrane comparison walks through that decision in detail, and if hacking is off the table entirely, see toilet waterproofing without hacking for the full menu of non-destructive options.
ClickBina does PU injection the transparent way: a flat RM650 for one bathroom ceiling, however many points it takes, backed by a 6-Month No-Leak Warranty — no per-point meter running while you watch. We diagnose before we drill, tell you honestly when injection is the wrong fix, and put the full price in writing on WhatsApp before any work starts. Klang Valley coverage, replies within the hour — send a photo of the leak for a same-day answer.
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