Staircase Calculator — NZ (Rise, Run & Dimensions)

NZ Building Code Clause D1 requires: riser height 150–220 mm, tread depth (going) 220–355 mm, and the comfort formula 2R + G = 550–700 mm. Handrails are mandatory on stairs with 4+ risers, positioned 900–1,000 mm above the stairline. All dimensions must comply unless specific exemptions apply.

Divide your floor-to-floor height (mm) by your preferred riser height (typically 175 mm). For example, 2,700 mm ÷ 175 = 15.4 risers, so round to 15 or 16. The actual riser becomes 2,700 ÷ 15 = 180 mm per step. Use this calculator to adjust dimensions until you achieve the ideal 2R + G formula.

Like-for-like internal stair replacements (same location, dimensions, materials) are typically exempt. However, new stairs, stairs serving a new level, or stairs outside NZS 3604 parameters REQUIRE a building consent. Check with your local council or an LBP-licensed builder before starting.

Stringers use H1.2 treated pine, H3.1 hardwood, or engineered laminated beam. Treads are 44 mm dressed pine, native hardwood (rimu, matai), oak, or engineered timber flooring. Handrails are typically 45 mm diameter hardwood or stainless steel. Always use licensed timber graded for structural use.

Straight timber staircases cost $3,500–$6,000 (supply + install). Hardwood or curved stairs range $6,000–$15,000. Floating or architectural stairs cost $15,000–$35,000+. Costs vary by builder experience, material selection, and whether building consent is required. Get 3 quotes with detailed line items.