Indoor vs Outdoor Glass Balustrades: Key Differences

While indoor and outdoor glass balustrades may look similar, there are important differences in specification, installation, and cost.

Glass Specification

Indoor: 15mm toughened glass is sufficient when a top handrail is incorporated. Without a handrail, 17.5mm or 21.5mm laminate is required for drops over 600mm. For low-level applications under 600mm, rules are more relaxed.

Outdoor: 15mm toughened with a handrail is the starting point. For exposed locations, high-traffic areas, or applications without a handrail where the drop exceeds 600mm, 17.5mm or 21.5mm laminated glass is required. Outdoor glass must also be considered for wind loading.

Material Choice

Indoor: Standard 304-grade stainless steel is fine for posts, clamps, and channels. Aluminium is also suitable.

Outdoor: 316 marine-grade stainless steel is strongly recommended. It resists corrosion from rain, salt air, and UV exposure. For high salt/coastal environments, we recommend mirror finish 316 for maximum resistance against tarnishing. Powder-coated aluminium is also a good choice for outdoor channels.

Building Regulations

Both indoor and outdoor balustrades must comply with Approved Document K:

• Indoor staircases: Minimum 900mm from pitch line
• Indoor landings/balconies: Minimum 1100mm
• Outdoor balconies/decking: Minimum 1100mm
• Loading: 0.74 kN/m horizontal force (residential)

Wind Loading

Outdoor balustrades, especially at height or in exposed locations, need to account for wind loading. This may affect:

• Glass thickness
• Post spacing
• Fixing method and substrate preparation

A structural engineer's input may be needed for multi-storey or highly exposed installations.

Cost Difference

Outdoor installations typically cost 10-20% more than indoor equivalents due to:

• Higher specification materials (316 stainless, thicker glass)
• More demanding substrate preparation
• Weather-dependent installation scheduling
• Additional fixings for wind resistance

Which Do You Need?

For indoor projects, standard specifications offer excellent value. For outdoor, invest in the right materials from the start — it's cheaper than replacing corroded fittings in 5 years.