Concrete leak sealing & injection · reference
How water gets through concrete, and what stops it.
Cracks, construction joints, lift pits, car park slabs, retaining walls and planter boxes — how each one leaks, how the causes are told apart from the dry side, and what a correct repair involves. Including the situations where injection is the wrong answer, which is more of them than the trade tends to admit.
Written around Brisbane, Gold Coast, Ipswich, Logan and the rest of South East Queensland, because the ground conditions genuinely change the answer — the four ground types behind almost every job.
This is a reference site. It carries out no building work — the enquiry form passes details to a licensed waterproofing contractor who can assess the issue.
FIG. 1 — Negative-side injection through mechanical packers. The holes are drilled at an angle and offset from the crack so they meet it at depth; the resin fills the crack from inside the wall rather than being smeared across the face.
Where to start
- HouseWater in a house or garageA wet patch on a garage wall, water appearing where the wall meets the floor, or a retaining wall soaking through into the room behind it.Start here
- Strata & body corporateWater in a buildingCar park ceilings dripping onto vehicles, a lift pit filling, planter boxes leaking into the level below. How the defect gets established, scoped and tendered so quotes can be compared.Start here
Before anybody is called
Is injection even the right fix?
Often it isn't. Resin injection seals a defined water path through concrete — a crack, a joint, a tie hole. It does nothing for a blocked ag line, a failed membrane, condensation, rising damp, or a wall that is still moving. Injecting any of those wastes the money and makes the real repair harder.
Fifteen situations where injection is the wrong repair are written up in full here, each with the giveaway sign and the trade that handles it instead. Before any of that, it is worth establishing where the water is actually getting in — the crack you can see is very often not the entry point.
Fifteen times injection is the wrong repairThe two resin grades, and when each is used
Polyurethane injection comes in two families. Which one is correct turns on a single question: will this crack ever dry out permanently?
- Hydrophobic PU
- Active leaks, and cracks that dry out over winter
- Hydrophilic PU
- Elements that stay wet all year round
Work it out before talking to anybody
Two pages that make a bad quote obvious
- Independent
- No building work is carried out here and no product is sold, so no page has a repair to protect
- Written for research, not for signing
- Claims are sourced and standards are named on the page, so they can be checked before anybody is contacted
- It says when to stop
- Where injection is the wrong fix, the page says so and names the trade that can actually help
- Nothing is gated
- No email wall, no consent gate, no tool that withholds its answer until a form is filled in
Contact a licensed waterproofer
Submit your details and they'll be passed to a licensed waterproofing contractor who can assess the issue.
Three photographs and a short description are usually enough for a leak to be identified — which three, and what each has to show.