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AS/NZS 1170.2AS/NZS 1170.2

Wind Loads (AS/NZS 1170.2)

Wind pressures link directly to any structural design calculator in your project - change a wind region, terrain category, or building dimension once and all connected beam, column, and wall calculations update automatically. Covers all AS/NZS 1170.2:2021 inputs for rectangular enclosed buildings under NCC 2022, with terrain category, topography, shielding, and directionality each overridable per wind direction for complex sites.

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What it calculates

Calculate site and design wind pressures to AS/NZS 1170.2:2021 in minutes. Terrain category, topography, shielding, and directionality can all be overridden for complex sites. Code references are shown on every output.

Code standards

  • AS/NZS 1170.2:2021

Who uses this calculator

Wind pressures link directly to any structural design calculator in your project - change a wind region, terrain category, or building dimension once and all connected beam, column, and wall calculations update automatically. Covers all AS/NZS 1170.2:2021 inputs for rectangular enclosed buildings under NCC 2022, with terrain category, topography, shielding, and directionality each overridable per wind direction for complex sites.

Apply the 2021 revision - new wind regions, updated terrain categories, and the Climate Change Multiplier - aligned to NCC 2022.

How it calculates

The Wind Loads (AS/NZS 1170.2) calculator determines site wind speeds and design wind pressures for rectangular enclosed buildings per AS/NZS 1170.2:2021. Wind is evaluated in all eight cardinal and ordinal directions, with terrain, topographic, shielding, and directionality multipliers applied independently per direction or as a single worst-case value.

Regional and site wind speed

The regional wind speed V_R is looked up from the wind region map for the chosen return period and importance level. The design site wind speed in each direction (V_sit,beta) is then:

V_sit,beta = V_R × M_d × max(M_z,cat × M_s, M_t)

Where:

  • M_d - wind directionality multiplier (default 0.95 for structural)
  • M_z,cat - terrain/height multiplier, interpolated from AS/NZS 1170.2 tables for terrain category and height (TC1 through TC4, evaluated at 10 m height intervals)
  • M_s - shielding multiplier (accounts for upwind shielding buildings)
  • M_t - topographic multiplier for hills, ridges, or escarpments
  • M_c - Climate Change Multiplier (AS/NZS 1170.2:2021 addition, applied per project requirements)

The maximum site wind speed across all eight directions, V_h, is the governing design wind speed. The calculator also reports the equivalent AS4055 wind class.

Design wind pressures

Velocity pressure at height h is derived from the design site wind speed. External pressure coefficients (C_pe) are applied to each building surface - windward wall, leeward wall, side walls, roof zones - per AS/NZS 1170.2 Cl. 5. Internal pressure coefficients (C_pi) depend on the enclosure condition: the calculator evaluates the dominant opening ratio (maximum ratio of opening area on one surface to total opening area on all other surfaces) to classify the building as enclosed, partially enclosed, or open.

Net design wind pressure on each surface combines external and internal components:

p = q_des × (C_pe - C_pi)

Outputs

The calculator reports V_R, V_h, the equivalent AS4055 wind class, and a load table of net wind pressures for each wall and roof zone in all relevant directions. A separate serviceability wind speed and pressures are also computed for deflection checks. All results are shown with their governing AS/NZS 1170.2:2021 clause references, and the load table can be linked to any ClearCalcs design calculator.

Assumptions and scope

The calculator assumes a rectangular enclosed building per Cl. 5, flat suburban terrain by default. Lee wind effects and special K factors are entered manually where required. A positive wind pressure acts toward the surface; a positive value in the load table indicates an inward or downward load on the building.

Related calculators

Wind Loads (AS/NZS 1170.2)→Bushfire Attack Level→Seismic Analysis→

What engineers say

Matt Ward company logo
You can analyze a beam and take the reactions from that beam and apply them directly to the column. Same if you have wind loads - you update those loads and everything else - the column and the footing - all follow suit.

Matt Ward

Principal Engineer, Ward Engineering

Read their story →
The most useful thing in ClearCalcs is the load linking. It saves time and cuts down on errors.

Jared

Owner/Engineer, JP Engineering

Frequently asked questions

What design standard does this calculator use?
The calculator implements AS/NZS 1170.2:2021 - Structural design actions: Wind actions. This is the 2021 edition required under NCC 2022, which introduced updated wind regions (including new Region D boundaries), revised terrain category definitions, and the optional Climate Change Multiplier for design wind speeds.
What are the key inputs?
Key inputs are wind region and design return period, terrain category (TC1 through TC4), site topography (hill, escarpment, or flat), shielding parameter, building height and plan dimensions, structure importance level, and cardinal direction weighting. Topographic multiplier (Mt), shielding multiplier (Ms), and directionality multiplier (Md) can each be overridden if site-specific data is available.
What outputs does the calculator return?
Outputs include regional wind speed (VR), site wind speed (Vsit,b) for each wind direction, design wind speed (Vdes,θ), velocity pressure (qz,des), and external and internal pressure coefficients for each building surface zone. Code clause references are shown alongside every calculated value.
Does the calculator include the Climate Change Multiplier introduced in 2021?
Yes. The 2021 edition introduced an optional Climate Change Multiplier (Mcm) to account for projected increases in wind speeds due to climate change. The calculator allows you to apply or omit Mcm depending on project requirements and client or AHJ direction.
How does this calculator differ from the earlier AS/NZS 1170.2:2011 version?
The 2021 revision updated wind region boundaries (particularly in coastal Queensland), revised terrain category multiplier tables, introduced the Climate Change Multiplier, and aligned definitions more closely with international standards. If your project is under NCC 2019 or earlier, use the AS/NZS 1170.2:2011 calculator. For NCC 2022 projects, this 2021 version is required.
Can I link wind loads from this calculator to my beam, column, and wall design calculations?
Yes. The 'Wind Loads for Load Linking' table in the results can be linked to any ClearCalcs structural design calculator in the same project. When you change a site input - wind region, terrain category, or building dimensions - all linked design calculations update automatically. No manual re-entry of wind loads between calculations.

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