Resin Injection August 2025 Newsletter
Basement waterproofing remains a critical concern for construction professionals, especially in urban environments where below-ground structures are increasingly complex. Among the most effective and minimally invasive solutions available today is resin injection, a technique that offers both structural reinforcement and watertight sealing.
Resin injection is normally required where the primary or existing waterproofing has failed. The structure is leaking. A remedy is required.
What Is Resin Injection?
Resin injection involves the use of polyurethane , Acrylic or epoxy resins to seal cracks, joints, and voids in concrete structures. The process typically includes:
- Identifying the source of water ingress
- Drilling ports along the affected area
- Injecting resin under pressure, allowing it to expand and fill the voids
- Curing, which forms a watertight seal that adapts to future movement
Polyurethane resins are particularly effective for active leaks, as they expand upon contact with moisture. Epoxy resins, on the other hand, are ideal for structural repairs due to their high bonding strength acrylic resins are often used where movement is likely.
Other resin options are available for different scenarios such as curtain wall installations and movement joints.
Diagnosing and Specifying the Solution
Once the source of a leak is diagnosed by the MacLennan surveying team, a tailored specification is prepared for remediation. This ensures that every intervention is based on a thorough understanding of the structure and the nature of the ingress.
- Large voids are chased out and filled with watertight concrete repair mortar.
- Cracks and deep voids are injected with our polyurethane resins, which react with water to seal the area permanently, preventing further ingress.
Tackling Joint Leaks with Precision
Very often it is joints, rather than cracks, that are the primary source of leaks in basement structures. The resin injection of construction joints must be carefully considered, as these joints can be designed to accommodate movement. Incorrect material selection or overfilling can lead to future complications.
MacLennan’s resin injection engineers bring over 30 years of experience to this highly specialised form of waterproofing. Our expertise have been applied to some of the most technically challenging projects in the UK.
Why It Matters for Basement Projects
Basements are especially vulnerable to water ingress due to their below-ground location. Traditional waterproofing methods, such as external membranes or tanking, can be disruptive, costly, and impractical or impossible for retrofit projects. Resin injection offers several advantages:
- Non-invasive: No need for excavation or extensive demolition
- Fast application: Most jobs can be completed within hours
- Durable: Resins are resistant to chemicals, movement, and long-term moisture exposure
- Cost-effective: Reduced labour and material costs compared to traditional methods
Applications in Design and Remediation
For architects and engineers, resin injection provides flexibility in both new builds and retrofit scenarios. It can be used to:
- Seal construction joints and cold joints
- Repair cracks caused by settlement or thermal movement
- Reinforce structural integrity in aging concrete
- Complement other waterproofing systems as a secondary barrier
Conclusion
Resin injection is not a one-size-fits-all solution, but when applied correctly, it offers a high-performance, low-disruption method for basement waterproofing. For construction professionals, understanding its capabilities and limitations is key to delivering resilient, watertight structures.
Resin injection will never be the primary waterproofing except in White tank scenarios for maybe a Carpark or tunnel.
For habitable construction where finishes are to be installed. Resin injection will be used to stop water ingress prior to installation of the waterproofing system.
Comprehensive Support from Survey to Completion
MacLennan surveyors investigate, report, and recommend the correct course of action, supplying fully itemised costs for all aspects of the work—including coordination with main contractors where necessary. The work is then carried out to the highest standards, leaving clients with the confidence that their basement is now fully watertight.
Please watch our resin injection video below...