What This Requirement Covers
Structural glass is used for balustrades, canopies, floors, roofs, and walls where transparency and aesthetics are priorities. Unlike conventional glazing supported by frames, structural glass must carry loads and resist impacts. The design must comply with BS EN 1991-1-1 (imposed loads), BS EN 12600 (safety), and specialist guidance.
Key Requirements
Types of Structural Glass
- Glass balustrades: Frameless or partially framed panels acting as guarding; must resist the horizontal imposed loads in Approved Document K (0.36-1.5 kN/m depending on building type)
- Glass floors: Laminated glass panels set into a supporting frame; must be designed for the full imposed floor load plus a point load of 2.0 kN
- Glass roofs and canopies: Overhead glazing must use laminated glass to prevent falling fragments; the outer pane should be toughened, the inner pane laminated
- Glass walls and fins: Glass used as a structural element to carry loads; requires specialist engineering design
Glass Types for Structural Use
- Toughened (tempered) glass: 4-5 times stronger than annealed glass; breaks into small fragments. Acceptable for guarding infill panels but not for overhead applications alone.
- Laminated glass: Two or more panes bonded with a PVB or SGP interlayer; remains in place when broken. Required for overhead glazing and structural balustrades.
- Toughened laminated glass: Combines the strength of toughened with the post-breakage retention of laminated. The preferred choice for structural applications.
Design Standards
- BS EN 1991-1-1: Imposed loads (barriers and balustrades)
- BS EN 12600: Impact safety classification
- IStructE Guide: Structural Use of Glass in Buildings (the primary UK design reference)
- CWCT: Centre for Window and Cladding Technology guides for facades
Practical Compliance Tips
- Always use a specialist glass engineer for structural glass design; standard structural engineers may not have the specific expertise
- Specify toughened laminated glass for all structural and overhead glazing applications
- Ensure edge treatments (polished, arrised) are appropriate for the application; exposed edges must be safe to touch
- Check that the glass support system (shoe, channel, patch fittings) is designed for the full load, including wind loads
- Consider long-term durability; laminated interlayers degrade in direct UV exposure
- Plan for glass replacement; structural glass panels are heavy and may require specialist equipment for installation
- Keep glass specifications, design calculations, and test certificates for the building file