Behind the Facade: Curtain Wall Types, Components and Structural Support in Modern Buildings

A contemporary building facade may appear to be a continuous surface of glass or metal, but it is usually a coordinated assembly of panels, framing, seals, joints and structural connections.

In many commercial and high-rise buildings, this outer layer is formed as a curtain wall, which is a lightweight, non-load-bearing facade attached to the building’s main structure. It supports its own weight and resists environmental forces such as wind, while transferring these loads through brackets and anchors to the building’s primary structural frame.

The Facade as a Building Envelope

In modern construction, the facade acts as the external envelope separating interior spaces from outdoor conditions. A curtain wall system commonly combines glass or opaque infill panels with mullions, transoms, gaskets, sealants, thermal breaks, drainage provisions and fixing systems.

The main components include:

• Mullions: Vertical members forming the primary facade grid.

• Transoms: Horizontal members fitted between mullions.

• Infill panels: Glass, metal, stone, terracotta or composite panels selected according to the design.

• Gaskets and sealants: Components used to limit air and water penetration at joints.

• Anchors and brackets: Connections fixing the facade to the building structure.

• Thermal breaks: Elements that reduce direct heat transfer through the framing.

Aluminium framing is widely used for mullions and transoms because it is lightweight, strong and corrosion resistant. It can also accommodate different finishes and panel configurations.

Main Curtain Wall System Types and Applications

Curtain wall systems differ mainly in the way their framing and panels are fabricated, assembled and installed.

Structural Support and Load Transfer

The facade depends on a defined load path between its components and the main building structure.

Framing

Vertical mullions and horizontal transoms support the facade panels and resist forces acting on the exterior. Their size and spacing are determined according to project requirements, including facade dimensions and wind pressure.

Anchors and Brackets

The framing is connected to the main building structure using anchors and brackets. These connections transfer the facade’s self-weight and environmental loads to the primary structure rather than relying on the infill panels to carry them.

Joints and Sealing

Curtain walls must also accommodate movement caused by expansion, contraction and movement of the building. Properly designed joints, gaskets and sealants help maintain weather resistance while allowing controlled movement within the facade system.

Benefits of Curtain Wall Systems

Beyond their structural role, curtain walls can provide several practical benefits when correctly designed and installed:

• Weather protection: Panels, seals, gaskets and drainage provisions help limit rain and air infiltration.

• Thermal performance: Insulated glazing and thermal breaks can reduce heat transfer through the facade.

• Natural light: Large glazed areas can allow more daylight into interior spaces.

• Lightweight enclosure: Curtain walls provide an external building envelope without functioning as a load-bearing wall.

• Faster installation: Unitised systems can reduce on-site installation time because complete facade panels are prefabricated before reaching the site.

These benefits depend on system design, material selection, fabrication and installation rather than on the facade type alone.

A Coordinated Facade System

Good building architecture depends on the connection between appearance and technical performance. A curtain wall may look visually light, but behind the finished surface is a carefully arranged system of framing, panels, fixings, joints and seals.

Whether a project uses a stick-built, unitised, semi-unitised or specialised glazing system, the basic principle remains consistent: the facade encloses the building and transfers its own loads and external forces to the primary structure, while the main structural system carries the building itself.