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Basement Waterproofing

# Basement waterproofing that keeps the water out.

Below-ground spaces fight constant hydrostatic pressure. We keep basements, undercrofts, lift pits and subterranean car parks dry using tanking, crystalline systems, cavity drainage and injection — new construction and remedial.

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Commercial & structural

## Below ground, water is always pushing in

A basement is surrounded by soil that holds water, and after rain that water exerts hydrostatic pressure against every below-ground surface — walls, slab, joints and penetrations. Unlike an above-ground wall that only has to shed water, a basement structure has to resist water that is actively being pushed through it, continuously.

This makes basement waterproofing one of the most demanding applications there is, and one of the least forgiving. A small defect that would be trivial above ground becomes a persistent leak below it. And because the water-facing (positive) side is buried against soil, defects usually can’t be reached from outside once the building exists.

There are two moments to get a basement right: during construction, with positive-side tanking and integral systems; and after the fact, with negative-side treatment from inside. We work in both — specifying and installing basement waterproofing for new builds, and remediating leaking basements and undercrofts without excavation.

Basement systems

## Keeping below-ground spaces dry

### Cementitious tanking

Positive and negative-side cementitious tanking systems that seal basement walls and slabs against hydrostatic pressure.

### Crystalline waterproofing

Crystalline systems that grow watertight crystals within the concrete, resisting water pressure from the buried side.

### Cavity drainage systems

Drained-cavity membrane systems that manage water to a sump and pump, providing a reliably dry internal environment.

### Crack & joint injection

Polyurethane and epoxy injection to seal the cracks, construction joints and penetrations that leak under pressure.

### Undercroft car parks

Waterproofing and leak remediation of subterranean and undercroft car parks, integrated with drainage and protection.

### Lift pits & tanks

Sealing of lift pits, pump wells and below-ground tanks where dry conditions are essential for plant and equipment.

Our approach

## Diagnosis first, always

#### Investigate the water

We establish where water is entering and under what pressure — diffuse seepage, discrete cracks, joints or penetrations — and whether the positive side is accessible.

#### Select the strategy

Tanking, crystalline, cavity drainage or a combination — chosen for the structure, the water pressure and whether we’re working new-build or remedial.

#### Prepare & treat

Surfaces prepared, active flows stemmed, cracks and joints injected, and the selected system applied to specification across walls and slab.

#### Verify dry conditions

The treated basement is monitored to confirm dry conditions are achieved and maintained before finishing and handover.

Basement waterproofing grades

## Matching the system to how the space is used

How dry a basement needs to be depends on what it’s for. A car park tolerates more than an archive. We specify to the intended environment.

- Hydrostatic pressure — below-ground systems must resist water actively pushed through the structure, not just shed it.
- Positive-side tanking — the ideal, water-facing barrier; installed during construction before backfill.
- Negative-side treatment — crystalline and cementitious systems applied internally for remedial work where the outside is buried.
- Cavity drainage — a managed-water approach that drains ingress to a sump, giving a dependable dry internal space.

Common questions

## Basement Waterproofing FAQs

Negative-side treatment — applied from inside — is exactly for this situation. Crystalline systems, cementitious tanking and crack injection seal the structure from the accessible internal face and resist the water pressure from the buried side, with no excavation. For persistent or heavy ingress, a cavity drainage system that manages water to a sump is a highly reliable alternative.

Cavity drainage is a managed-water system: a dimpled membrane lines the internal walls and floor, any water that enters is channelled behind it to a perimeter drain and sump, and a pump discharges it. Rather than trying to resist every drop, it reliably collects and removes water — ideal for basements where absolute exclusion is difficult to guarantee.

Yes. For new builds we specify and install positive-side tanking, integral crystalline admixture systems and correctly detailed joints and penetrations before backfill — getting it right at the one stage when the water-facing side is fully accessible is always the best-value approach.

Below-ground structures can transmit moisture as vapour through the concrete without obvious dripping, producing that characteristic damp, musty basement smell along with efflorescence. Treating the structure with a crystalline or tanking system reduces this vapour transmission and, combined with ventilation, resolves the dampness.

Related services

## Explore related work

Concrete Leak Sealing
Crack Injection
Car Park Waterproofing
Remedial Waterproofing
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## Get your basement dry

A damp or leaking basement wastes usable space and threatens the structure. Book an assessment and we’ll specify a system to keep it dry.

Request an assessment
Call 0488 773 232