01 / Site & Building Inputs
For buildings ≤25 m, use h as both reference height and building height (AS/NZS 1170.2 cl. 2.2).
Formula: Vdes,μ = VR × Mc × Md × (Mz,cat × Ms × Mt)
Dynamic pressure: q = 0.5 × ρ × Vdes,μ² × Cshp × Cdyn
Where ρ = 1.2 kg/m³ (air density per AS/NZS 1170.2)
Dynamic pressure: q = 0.5 × ρ × Vdes,μ² × Cshp × Cdyn
Where ρ = 1.2 kg/m³ (air density per AS/NZS 1170.2)
02 / Result
Enter inputs to calculate wind pressure
AS/NZS 1170.2:2021 — scope and limitations. This tool calculates design wind pressure for enclosed rectangular buildings with flat or pitched roofs up to 25 m height. Results are indicative only — actual design pressures require consideration of: net pressure coefficients (Cp,n) for specific element types (cladding, fasteners), internal pressure coefficients (Cpi), local pressure factors for corners and edges (AS/NZS 1170.2 Table 5.3), and building-specific aerodynamic shape factors. Buildings over 25 m height, irregular shapes, or in cyclonic regions require specific engineering design. For NZS 3604 wind zone determination, use the simplified regional wind speed method. All results must be verified by a Chartered Professional Engineer.
Regional Wind Speeds — AS/NZS 1170.2 Table 3.1 (ultimate limit state)
| Region | V_R (m/s) | Description | Typical Areas |
|---|---|---|---|
| Region A | 30 | Very low | Parts of Southland, Otago, inland Canterbury |
| Region B | 37 | Low | Parts of Waikato, Bay of Plenty, Taranaki, South Island |
| Region C | 45 | Medium | Auckland, Wellington, Christchurch, most NZ |
| Region D | 55 | High | Exposed coastal: Far North, Taranaki, West Coast, Sub-Antarctic islands |
Mc (climate change): IL1 = 1.00, IL2 = 1.00, IL3 = 1.10, IL4 = 1.15 per AS/NZS 1170.0. Md (directional) = 0.85–1.00 per Annex C. For residential design, use conservative Md = 0.9 or engineering assessment.