Designing a staircase in New Zealand requires careful planning to ensure it is safe, functional, and compliant with the New Zealand Building Code (NZBC). Here are 13 key things to consider, including relevant clauses from the NZBC:
1. Compliance with NZBC Clause D1: Access Routes
- Purpose: Stairs must provide safe and accessible passage between levels.
- Requirements:
- Stairs must have consistent riser heights and tread depths to prevent tripping.
- Maximum riser height: 190mm.
- Minimum tread depth: 240mm.
- Maximum pitch: 37 degrees.
2. Safety Features (NZBC Clause F4: Safety from Falling)
- Balustrades and Handrails:
- Required for stairs with a vertical drop of more than 1 meter.
- Balustrades must be at least 900mm high for residential stairs.
- Gaps in balustrades must not allow a 100mm sphere to pass through (to prevent children from climbing or falling).
- Non-Slip Surfaces: Treads should have a non-slip finish to prevent accidents.
3. Width of Stairs (NZBC Clause D1)
- Minimum Width:
- Residential stairs: 600mm clear width.
- Public or commercial stairs: 1000mm clear width.
- Ensure the width accommodates furniture movement if needed.
4. Headroom (NZBC Clause D1)
- Minimum Headroom:
- At least 2 meters of clear headroom above the stairs to prevent head injuries.
5. Number of Steps
- Maximum Number of Risers:
- No more than 16 risers in a single flight without a landing.
- Landings:
- Required between flights to provide a resting point.
- Minimum landing length: 900mm.
6. Tread and Riser Dimensions (NZBC Clause D1)
- Consistency:
- All treads and risers must be uniform in size to ensure safety.
- Maximum Riser Height: 190mm.
- Minimum Tread Depth: 240mm.
7. Handrails (NZBC Clause D1)
- Height:
- Handrails must be between 900mm and 1000mm above the pitch line of the stairs.
- Continuity:
- Handrails must extend at least 300mm beyond the top and bottom steps.
- Gripability:
- Handrails must be easy to grip, with a diameter of 30–50mm.
8. Lighting (NZBC Clause G8: Artificial Light)
- Adequate Lighting:
- Stairs must be well-lit to ensure visibility and safety.
- Use light fixtures that illuminate the treads evenly.
- Switches:
- Install switches at the top and bottom of the stairs for convenience.
9. Materials and Durability (NZBC Clause B2: Durability)
- Material Selection:
- Choose materials that are durable, non-slip, and resistant to wear and tear.
- Common materials include timber, steel, and concrete.
- Weather Resistance:
- For outdoor stairs, use materials that can withstand New Zealand’s climate (e.g., treated timber or stainless steel).
10. Accessibility (NZBC Clause D1)
- Inclusive Design:
- Consider adding a ramp or lift for accessibility if required.
- Ensure stairs are designed to accommodate people with limited mobility where possible.
11. Structural Integrity (NZBC Clause B1: Structure)
- Load-Bearing Capacity:
- Stairs must be designed to support expected loads, including people and furniture.
- Foundation:
- Ensure the stairs are securely anchored and supported, especially for outdoor or freestanding stairs.
12. Aesthetics and Design
- Style:
- Choose a design that complements the architecture of your home.
- Finishes:
- Consider finishes that enhance the appearance while maintaining safety (e.g., non-slip coatings).
13. Maintenance and Longevity
- Ease of Maintenance:
- Design stairs that are easy to clean and maintain.
- Durability:
- Use materials and finishes that will withstand regular use and weather conditions.
Bonus Tip: Professional Help
- Design: Work with an architect or designer to ensure the stairs meet all regulatory and functional requirements.
- Builders: Hire licensed builders who are familiar with NZBC requirements.
- Inspections: Ensure the stairs are inspected during and after construction to verify compliance.
By considering these factors and adhering to the relevant NZBC clauses, you can design a staircase that is safe, functional, and compliant with New Zealand’s building standards. Always consult with professionals and your local council to ensure your project meets all legal requirements.