BRANZ Maps

About the tool

BRANZ Maps is an online mapping tool that helps users understand key building‑related environmental conditions across New Zealand. By entering a location, users can view mapped information such as earthquake risk, wind exposure and corrosion severity. The tool supports better early‑stage design decisions and helps users interpret how building standards apply to different parts of the country.

What you’ll find on the maps

Earthquake zones

These show how strongly an area may shake in an earthquake. The zones are based on New Zealand building standards and have been updated to reflect changes made after the Canterbury earthquakes.

Four earthquakes zones - zone 1 to zone 4 - are shown on a map of the North and South Islands in Figure 5.4 of NZS 3604:2011 Timber-framed buildings.

The earthquake zones in BRANZ Maps are modified versions of those. The zones are modified so that they better align with NZS 1170.5:2004 Structural design actions - Part 5: Earthquake actions - New Zealand.

BRANZ Maps also include the changes to the zone boundaries in the Canterbury region introduced by the New Zealand Building Code clause B1 compliance document published in August 2011.

Corrosion (exposure) zones

These indicate how exposed an area is to sea salt, which can affect how quickly materials like fixings and claddings may corrode. Areas closer to the coast, estuaries or offshore islands generally have higher exposure.

Three exposure zones - zone B, zone C and zone D - are shown on a map of the North and South Islands in Figure 4.2 of NZS 3604:2011.

The corrosion zones in BRANZ Maps are our interpretation of the exposure zones in NZS 3604:2011.

The zones relate to the severity of exposure to wind-driven salt, with B being low risk, C medium risk and D high risk.

Zone D includes:

• all offshore islands
• the area within 500 m of the coastline of New Zealand, including harbours
• the area within 100 m of tidal estuaries and sheltered inlets.

BRANZ has not attempted to define precisely what is or isn't a tidal estuary or sheltered inlet, so our maps are technically conservative in those areas.

Building Code compliance document E2/AS1 (2011) includes an exposure zone E, which is beachfront regions subject to rough seas and surf beaches. NZS 3604:2011 contains the comment: "For the purposes of NZS 3604, the corrosion protection requirements for structural fixings in exposure zones D and E are identical..."

Microclimatic factors need to be considered in all locations.

Wind regions and wind zones

These give an indication of typical wind strength and shelter across the country. They are based on BRANZ research and building standards and are intended to help with early design decisions.

Wind zones are an output from a 2014 research project at BRANZ. The project aimed to see if the calculation of wind zones (in accordance with NZS 3604:2011) could be automated using GIS (geographic information system) software. The method for calculating wind zones in NZS 3604:2011 is a simplification of the method described in AS/NZS 1170.2:2011 Structural design actions - Part 2: Wind actions.

Several approximations were made in the process of creating the map. Therefore, the wind zones must be treated as indicative and used only as a reference when calculating site-specific wind speed.

BRANZ does not recommend using BRANZ Maps as the primary source of wind zone data for making bracing calculations or preparing building consent application documents if other more reliable data (such as an up-to-date council map) is available.

Initial user testing has shown that the wind zones in BRANZ Maps are likely to be inaccurate near escarpments or cliffs.

Climate zones

Climate zones 1 to 6 are taken from Appendix C in H1/AS1 and H1/VM1 5th edition amendment 1. Climate zone boundaries consider climatic data and territorial authority boundaries. Appendix C has a map and a table showing which zone(s) apply to each territorial authority.

Rainfall intensity

Rainfall intensity values are sourced from NIWA's HIRDS calculator and correspond to a 10-minute rainfall intensity with an annual probability of exceedance of 10%. These values can be used in conjunction with clause E1 of the Building Code. For other storm durations, consult the HIRDS calculator

How to use this information

BRANZ MAPS are designed as a general guidance tool. They’re useful for understanding broad conditions at a location, checking early design assumptions, and supporting learning and discussion.

However, the zones are not a substitute for site‑specific assessments. Local conditions, terrain and council‑provided maps can be more accurate, especially for things like wind and complex sites. Always use the most reliable, up‑to‑date information when making design decisions or preparing building consent documents.