Curtain walling, shopfronts and commercial windows: understanding the differences

A window sits inside an opening formed by the surrounding wall. The wall supports it, and the window's job is to close that opening while letting in light and, where it opens, air. Windows are usually specified unit by unit from a schedule. The main questions are opening type, ventilation, thermal and acoustic performance, and how the frame ties into the wall's insulation and weather line.

Shopfront framing is designed for large areas of glass at ground level, typically spanning one storey between floor and fascia. It usually incorporates the entrance door. The focus is appearance, display, security, customer access and safety glazing. Shopfronts are often installed in existing buildings and on units that want to keep trading.

Curtain walling is a façade in its own right. It hangs off the building structure, can run over many storeys and passes past floor slabs and columns. Because it forms the building envelope, it has to deal with structural fixing, building movement, drainage, air and water tightness and interfaces with the roof and other cladding. It is normally designed and priced as a project-specific package.

A simple way to think about the differences:

Many commercial buildings combine all three: a curtain walled entrance or stair core, a shopfront at ground level and windows above. The junctions between them are where weather problems tend to start, so it helps to agree early who designs and installs each junction.

If you are unsure, describe the building and what you want to achieve. Elevations or photographs usually make the answer clear quickly.