Closed-cavity facades, explained

Technical content reviewed 24 August 2026.

Scope note. Closed-cavity facade performance is system- and project-specific. The selected manufacturer, geometry, pressure regime, controls and maintenance strategy must be verified through the project design and evidence route.

A closed-cavity facade places a protected cavity between an outer skin and an inner insulated glazing line. Conditioned or dried air is normally supplied to manage moisture and keep the cavity environment stable. Solar-control blinds can sit inside the protected cavity, avoiding direct external exposure while allowing a highly glazed architectural expression.

The system is more than two panes of glass

The facade depends on the relationship between the inner and outer skins, cavity seals, air-distribution path, pressure strategy, drainage, shading device and controls. Mullions, transoms, unit joints, perimeter seals, slab-edge interfaces and replacement strategy all need to work as one system. A change to cavity depth or module geometry can affect air flow, blind clearances, structural behaviour and fabrication.

What the design team must coordinate

• Geometry and structure: grids, unit sizes, glass build-ups, supports, movements and tolerances.
• Environmental performance: thermal modelling, solar gain, condensation risk, air permeability and weather resistance.
• Cavity operation: air-supply duty, distribution, monitoring, alarms, access and failure strategy.
• Interfaces: perimeter fire, air and water seals; spandrels; slab edges; adjacent roofs and cladding.
• Maintenance: blind access, glass replacement, filters, controls and safe inspection routes.

Fabrication and commissioning evidence

Manufacturing information should bind each unit or type to profiles, glass, gaskets, seals, vents, blind components, tolerances and assembly checks. Project calculations and system limits should be reflected in the drawings and bills of materials. Commissioning records should identify the tested zone, settings, readings, date and responsible party. A generic manual is useful background but does not replace the project configuration.

When a closed cavity is a sensible option

The approach can be valuable where transparency, solar control, appearance and protected shading justify the added services and controls. It also introduces operational dependencies that need an owner for the building’s life. Early option review should compare performance, buildability, replacement, controls and maintenance—not only the elevation.

For the wider system review, see facade engineering and embodied carbon in curtain walling.