Balustrades are critical safety features in buildings, preventing falls and ensuring safe access between levels. In New Zealand, balustrade design and installation must comply with strict safety standards outlined in the New Zealand Building Code (NZBC) and other relevant regulations. Below is a detailed breakdown of what you need to know about balustrade safety standards.
1. Key NZBC Clauses for Balustrades
Balustrades are primarily governed by the following NZBC clauses:
a. Clause F4: Safety from Falling
- Purpose: To prevent people from falling from one level to another.
- Height Requirements:
- Residential Buildings: Balustrades must be at least 1.0 meter high.
- Commercial/Public Buildings: Balustrades must be at least 1.0 meter high for stairs and 1.1 meters high for other areas.
- Openings and Gaps:
- Gaps in balustrades must not allow a 100mm sphere to pass through (to prevent children from climbing or falling).
- For pool fences, this requirement is even stricter under the Fencing of Swimming Pools Act 1987.
b. Clause D1: Access Routes
- Purpose: To ensure safe and accessible passage within buildings.
- Handrails:
- Handrails are required for stairs and ramps.
- Handrails must be between 900mm and 1000mm above the pitch line of the stairs.
- Handrails must extend at least 300mm beyond the top and bottom steps.
- Continuity: Handrails must be continuous and easy to grip, with a diameter of 30–50mm.
c. Clause B1: Structure
- Purpose: To ensure balustrades are structurally sound and can withstand expected loads.
- Load Requirements:
- Balustrades must withstand a horizontal load of 0.5 kN/m (kilonewtons per meter) for residential applications.
- For commercial or public buildings, the load requirement may be higher (e.g., 1.5 kN/m).
d. Clause F9: Means of Restricting Access to Residential Pools
- Purpose: To prevent unsupervised access to pools by children under 5.
- Height: Pool fences, including glass balustrades, must be at least 1.2 meters high.
- Gaps: The gap between the bottom of the balustrade and the ground must not exceed 100mm.
2. Types of Balustrades and Their Safety Requirements
Balustrades can be made from various materials, each with specific safety considerations:
a. Glass Balustrades
- Safety Glass:
- Must comply with AS/NZS 2208: Safety Glazing Materials in Buildings.
- Use toughened or laminated glass to prevent injury if broken.
- Thickness:
- For balustrades up to 1.0 meter high, use at least 6mm toughened glass or 6.38mm laminated glass.
- For balustrades over 1.0 meter high, use thicker glass (e.g., 8mm toughened or 8.38mm laminated).
- Edge Finishing:
- Glass edges must be smooth and polished (e.g., seamed, pencil-polished, or arrised).
b. Timber Balustrades
- Strength:
- Timber must be durable and resistant to rot, especially in outdoor or wet areas.
- Spacing:
- Gaps between timber balusters must not allow a 100mm sphere to pass through.
c. Metal Balustrades
- Material:
- Use corrosion-resistant materials (e.g., stainless steel or powder-coated aluminum) for outdoor applications.
- Spacing:
- Gaps between metal balusters must not allow a 100mm sphere to pass through.
3. Specific Applications and Additional Requirements
a. Pool Fences
- Height: At least 1.2 meters.
- Gaps: No gaps larger than 100mm.
- Climbable Elements:
- Avoid horizontal elements that children can climb.
- Glass balustrades are ideal as they provide a smooth, unclimbable surface.
b. Stairs and Ramps
- Handrails:
- Required on at least one side of stairs and both sides of ramps.
- Must be between 900mm and 1000mm high.
- Visibility:
- Ensure balustrades do not obstruct visibility, especially in public or commercial buildings.
c. Balconies and Decks
- Height: At least 1.0 meter for residential buildings.
- Load-Bearing Capacity:
- Must withstand a horizontal load of 0.5 kN/m for residential applications.
4. Compliance and Inspections
- Building Consent:
- Balustrades generally require a building consent, especially if they are part of a pool fence or structural element.
- Inspections:
- Balustrades must be inspected during and after installation to ensure compliance with the NZBC and relevant standards.
- Certification:
- Installers should provide certification that the balustrade meets all safety and performance requirements.
5. Common Mistakes to Avoid
- Incorrect Height:
- Failing to meet the minimum height requirements (e.g., 1.0m for residential, 1.2m for pools).
- Improper Spacing:
- Allowing gaps larger than 100mm between balusters or at the base of the balustrade.
- Inadequate Fixings:
- Using insufficient or incorrect fixings, leading to structural failure.
- Non-Compliant Materials:
- Using non-safety glass or untreated timber in outdoor applications.
6. Summary of Key Safety Standards
| Aspect | Requirement |
|---|---|
| Height | 1.0m (residential), 1.1m (commercial stairs), 1.2m (pool fences) |
| Gaps | No gaps larger than 100mm |
| Load-Bearing Capacity | 0.5 kN/m (residential), 1.5 kN/m (commercial) |
| Handrails | 900–1000mm high, continuous, 30–50mm diameter |
| Glass Balustrades | Toughened or laminated, min 6mm thick, smooth edges |
| Pool Fences | 1.2m high, no climbable elements, max 100mm gaps |
Conclusion
Balustrades are essential for safety in buildings, and their design and installation must comply with strict standards under the New Zealand Building Code (NZBC). Key considerations include:
- Height and gap requirements to prevent falls.
- Use of safety materials (e.g., toughened glass, corrosion-resistant metals).
- Compliance with load-bearing and structural requirements.
- Proper installation and inspection to ensure safety and durability.
Always consult with professionals (e.g., architects, builders, or engineers) to ensure your balustrades meet all legal and safety requirements.