Whenever a structure sits below the water table, hydrostatic pressure pushes groundwater through the smallest of imperfections. Add in the fact that substructures are often made up of multiple elements — walls and a floor with joints between — and the risk becomes inevitable.

Even a well-built, watertight structure can develop problems over time. Common causes include:

• poor drainage around the structure,

• building or ground movement causing cracking,

• changes in the surrounding water table due to nearby construction.

Traditional tanking

The most common method for waterproofing a sub-structure is tanking. This relies on bonding sheets or impermeable membranes to the outer surface of the substructure.

While tanking can be effective, it depends heavily on good workmanship and joint integrity. Any damage or poor installation can allow water through, leading to damp patches, corrosion, or even structural issues. Once the membrane is breached, the entire foundation can be compromised and fixing it is rarely quick or cheap.

Whatever the cause, failure of the tanking system can result in anything from the appearance of a damp patch on the wall and damage to surface finishes all the way to corrosion and potential structural failure. Often, once a membrane is breached, the whole concrete foundation will be vulnerable to the presence of migrating groundwater and, potentially, corrosion of the reinforcing steel if chlorides are present in the groundwater

The modern alternative: resin injection

Modern, sustainable alternatives like as resin injection can provide a cheaper, less disruptive waterproofing alternative.

Ground engineering specialist Mainmark has developed a solution that involves injecting a chemically stable, water-resistant resin into the ground surrounding a structure. Once injected, the resin will expand and harden creating an impermeable barrier on the outside of the wall or floor slab.

It is suitable for use with numerous materials including, concrete, brick and stone, and fully complies with BS 8102:2022 (Protection of Below Ground Structures Against Water Ingress), ensuring performance in line with recognised UK waterproofing standards.

A non-invasive solution

How it works:

• First, small holes are first drilled at specified intervals through the wall or floor. This will ensure an even distribution of resin.

• Injection tubes are inserted

• Resin is injected under pressure into the surrounding ground, filling any cracks and voids.

• In place, the resin expands, cures and hardens to form an impermeable layer to help prevent further water ingress.

This solution is ideal for basements and substructures, underground car parks, tunnels and service chambers.

For engineers and contractors tackling water ingress below the water table, resin injection represents a smart approach combining precision, performance, and practicality to keep substructures dry for decades to come.