External Waterproofing

External Basement Waterproofing

External basement waterproofing is a critical part of protecting new-build basements and earth-retaining structures from water ingress. Below-ground walls are exposed to groundwater and moisture under hydrostatic pressure, which can cause long-term structural damage if not properly managed.

During construction, external waterproofing systems are installed to resist water pressure and protect foundation walls before backfilling takes place. These systems are typically specified for new builds or major structural works where full external access is available.

External waterproofing systems usually combine primary barrier protection with secondary drainage and protection layers to ensure long-term performance.

External Waterproofing Systems

A typical external waterproofing system incorporates multiple components working together to protect the structure and manage groundwater.

Primary External Waterproofing Layer

The primary layer is applied directly to the external face of the structure to create a continuous waterproof barrier. These coatings are designed to resist water pressure and extend down to the base of the foundation.

• Flexible cementitious and bitumen-based waterproof coatings

Secondary External Drainage & Protection Layer

Secondary layers are installed over the primary waterproofing to protect it during backfilling and help manage groundwater. External cavity drain membranes create a drainage path that directs water away from the structure to a suitable discharge point, such as a French drain.

• External cavity drain membranes

External Waterproofing Membranes

External cavity drain membranes are available as geocomposite systems, incorporating an integrated filter layer to prevent fine particles from entering and blocking the drainage channels.

These membranes are suitable for use at significant depths and provide both drainage and mechanical protection to the primary waterproofing layer.

Installation

External drainage membranes are supplied in rolls and are typically fixed to external insulation or substrate using compatible mechanical fixings. Correct detailing at joints, terminations and outlets is essential for system performance.

Backfilling & Protection

Once installed, the primary waterproofing layer must be protected from damage during backfilling and as the structure settles. Sharp aggregates and debris can compromise waterproof coatings if not adequately protected.

Drainage membranes provide a sacrificial protective layer and allow for movement as the building settles, helping maintain the integrity of the waterproofing system.

Why Buy from Waterproof & Dry?

Waterproof & Dry are independent specialists in basement and structural waterproofing systems, supplying reliable external waterproofing solutions for construction projects across the UK.

Our in-house technical team offers free advice to help you select the right combination of products for your ground conditions, structure and build programme.

Need advice on external waterproofing or internal tanking alternatives? Call us on 0117 332 4747.