PU Injection & Crack Repair
PU injection stops water at the crack. It is the right method when the leak is active, the crack is non-structural and the surface waterproofing cannot be replaced — typically basement walls, lift pits, retaining walls and construction joints. Where the crack is structural, epoxy injection is used to re-bond the concrete; PU is used to stop the water.
Common defects we treat
- Active drip or trickle through a concrete crack
- Wet basement or lift pit wall with visible crack
- Construction joint leakage between pours
- Leakage at pipe penetration through slab or wall
- Damp patches on retaining wall fed by external groundwater
Method on site
Crack mapping and access
Crack pattern, length, width and water flow recorded. Surrounding finish and reinforcement layout considered before drilling location is set.
Drilling and packer installation
Holes drilled at alternating angles across the crack at spacing matched to the crack depth. Packers torqued in place, ready for resin pumping.
Resin pumping
PU resin pumped at controlled pressure starting from the lowest packer upwards (for vertical cracks). Resin reacts with water, expands and seals the crack from inside.
Packer removal and surface make-good
Packers removed after the resin has set. Drill holes filled with non-shrink grout. Surface finish reinstated and cleaned.
Inspection and surface waterproofing
Crack monitored for re-emergence over a holding period. Surface waterproofing applied as a secondary layer where the substrate justifies it.
Materials we use
- Hydrophilic and hydrophobic PU resins for active leak stopping
- Acrylic gels for fine cracks and curtain injection behind slab
- Epoxy injection resins for structural crack rebonding
- Mechanical packers in stainless steel or zinc-plated steel
Deliverables to the client
- Crack mapping and injection record
- Method statement with material data sheets
- Photo record of packer layout and resin penetration
- Recommendation on secondary surface protection