Glass deflection refers to the temporary bending or displacement of a glass panel when subjected to external forces such as wind load, snow load, or thermal stress. When wind pressure pushes against a glass facade, the center of the panel bows inward while the edges remain fixed within the frame. This maximum inward displacement at the center is measured in millimeters and is critical for ensuring both structural safety and visual comfort.
Excessive deflection can cause seal failure in insulated glass units (IGU), lead to glass breakage, create optical distortions, and compromise the building envelope integrity. Industry best practices suggest maximum allowable deflection limits—typically L/60 to L/175 of the shorter span depending on application and glass type.