Injection grouting stops active water ingress by injecting a polyurethane or acrylic resin directly into a leaking crack or construction joint, where it expands and cures to seal the water path from within the structure, with no excavation.
It is the method of choice for a wall or slab that is already leaking through a defect, especially below ground where the outside face cannot be reached. The resin travels into the crack, follows the water, and cures into a flexible or rigid seal that blocks the route the water was using.
Where injection grouting is used
Basement and retaining walls leaking through cracks or joints, construction joints in slabs and tanks, lift pits and below ground structures, and negative side situations where the wall cannot be excavated. It works where a surface coating cannot, because it treats the defect itself rather than the face around it.
PU resin and acrylic gel
Polyurethane resins react with water and foam to fill and seal an actively leaking crack, ideal for stopping a live flow. Acrylic gels penetrate finer cracks and the surrounding structure to form a flexible waterproof zone, suited to hairline defects and permanent flexibility. We select the resin for the crack width, the water pressure and whether the defect moves.
| Resin | Best for |
|---|---|
| Polyurethane foam | Active, flowing leaks in cracks and joints |
| Acrylic gel | Fine hairline cracks and flexible sealing |
How the injection is done
We drill injection ports along the crack at an angle that intersects it, flush the crack, then inject the resin under pressure through packers until it fills the defect and stops the flow. The ports are removed and made good. Because the resin cures in contact with water, the leak itself guides the seal to the right place.
Active crack sealing
PU foam injected into a live leaking crack to stop the flow.
Construction joint treatment
Sealing the joints between concrete pours in slabs, walls and tanks.
Negative side, no excavation
Treating below ground structures from the inside when the outside cannot be reached.
Fine crack penetration
Acrylic gels for hairline defects and flexible waterproof zones.
Related services
Book an injection survey
We confirm the fee and scope before we attend. The inspection fee is deducted from the works if you proceed.
Book an inspection