Designing and engineering a shelter isn’t just about appearance or utility, it is about standing up against the force of nature. In Australia, wind is one of the most important factors affecting building structures, particularly in the remote, open, and cyclonic regions. This is why it is very important to understand the different wind classifications to ensure that safe, durable shelters are being built.
This blog will discuss the wind regions, terrain categories, & importance levels in Australia, and how these factors intertwine with the n2 wind rating, so that in future, you may approach your project with confidence and knowledge.
What Is Wind Region Classification?
Australia is split into different wind zones based on the likelihood and severity of extreme weather events in those areas. AS/NZS 1170.2:2021 is the national standard for calculating wind load. The following classes reflect this criteria.
Knowing about wind regions ensures that every shelter is designed and engineered to withstand the wind conditions most likely to affect its location.
The Four Wind Regions of Australia
Every custom Allshelter structure is made to last. We use premium, engineered materials that meet or exceed Australian safety and compliance standards. From strong winds to large snow loads, our buildings are designed to withstand extreme conditions without compromising safety or use.
Region | Description | Ultimate Regional Wind Speed |
Region A | Normal conditions with moderate wind likelihood | Up to 162 km/h |
Region B | Intermediate zone near cyclone regions | Up to 205 km/h |
Region C | Cyclonic region, including Northern Australia | Up to 238 km/h |
Region D | Severe cyclonic regions like parts of WA and NT | Up to 288 km/h |
Shelters in Region C and D require additional reinforcement and design considerations to meet safety standards.
What Are the Different Types of Terrain?
The area around the wind speed measurement is also very important. This is known as the Terrain Category, which helps determine how wind moves and affects a building.
The Three Main Terrain Categories
- Terrain Category 1
Very open places, such as flat plains or coastal areas with little to no obstacles. - Terrain Category 2 (Standard for Allshelter Designs)
Terrain that is open yet has few trees and low-rise structures in the way. Most of the time, this includes rural and industrial areas. This is the default terrain setting for all Allshelter-designed systems, and it fits with the n2 wind rating classification. - Terrain Category 3
In suburban or highly developed areas, there are often obstacles ranging from 3 to 10 meters high.
By defaulting to Terrain Category 2, Allshelter finds a good compromise between realistic wind exposure and structural efficiency. This ensures that your shelter is neither too divided nor too consolidated.
Understanding Importance Levels
Not all constructions have the same chance of failing. The Importance Level of a structure indicates its significance for human safety, infrastructure, and operations.
Importance Level Breakdown:
- Importance Level 1:
Structures that are low-risk and often empty, like isolated storage shelters. - Importance Level 2:
This is the standard level for most shelters that have a moderate number of people and a moderate economic value. Most of Allshelter’s commercial and industrial projects fall into this category. - Importance Level 3:
Facilities with a lot of risk where failure would have significant effects on people or the environment. - Importance Level 4:
Important infrastructure like hospitals, emergency response centres, or dangerous facilities. Fabric shelters are usually not suitable for this group.
Importance levels are part of the formula used to determine the final design wind speed and are directly connected to the application of the n2 wind rating.
What Is N2 Wind Rating?
The n2 wind rating is a structural classification applied to buildings or shelters expected to withstand a design wind speed derived from a specific combination of:
- Wind Region
- Terrain Category
- Importance Level
- Design Life (typically 25 years for Allshelter structures)
- Structure Height (commonly averaged at 10m)
This grade ensures that the shelter can withstand the daily wind pressures in the area without compromising safety or durability.
For example:
A shelter in Region B2, with an Importance Level of 1, a Terrain Category of 2, a 25-year design life, and an average height of 10m, has a design wind speed of 163 km/h, which gives it an n2 wind rating.
By following the n2 wind rating, our shelters meet industry standards for structural integrity in a wide range of situations, including construction, mining sites and logistical activities.
Design Wind Speed Calculations: A Closer Look
The table below shows how design wind speed is calculated across different regions, assuming Terrain Category 2 and a 25-year design life.
Region | Ultimate Wind Speed (km/h) | Importance Level 1 | Level 2 | Level 3 |
Region A0 / A1-A5 | 162 | 148 | 154 | 162 |
Region B1 | 205 | 164 | 177 | 194 |
Region B2 | 205 | 163 | 176 | 192 |
Region C | 238 | 192 | 207 | 255 |
Region D | 288 | 226 | 246 | 271 |
As seen above, Region A shelters typically fall under the n2 wind rating when Importance Level 2 is used, which is the most common application for temporary or semi-permanent shelters.
Why Wind Ratings Matter for Fabric Shelters
Using the wrong wind rating can not only cause the structure to fail, but it can also result in downtime, loss of commodities, or even endanger people. That’s why Allshelter applies engineering tailored to each region. This makes sure that each project is:
- Designed to suit its specific environment and wind conditions for every shelter.
- Entirely in line with AS/NZS 1170.2:2021 to meet insurance and legal requirements.
- Built to last and keep your things safe in the real world.
There is no way to make everything fit in one size. Your wind rating will determine the design and materials required for your shelter, whether it is a permanent dome shelter or a towable fabric shelter suitable for setting up in a remote area.
Engineering for Safety and Longevity
We don’t take shortcuts at Allshelter. During the consultation phase, every structure undergoes a wind load assessment to determine the appropriate engineering inputs for its design. This is how the process works:
- Location Mapping
We utilise official wind maps and technologies to determine the wind zone, projected terrain exposure, and other environmental characteristics. - Design Matching
We use the correct N2 wind rating or higher, depending on the location of the shelter and its intended purpose. - Fabrication and Delivery
After being designed, shelters are built to order and sent to your site for quick assembly.
How N2 Wind Rating Works in the Real World
In Australia, the n2 wind rating is very common, especially in Regions A and B. It is a reliable standard for semi-permanent shelters that strikes a good compromise between safety and cost-effectiveness.
Here are some of the most important benefits:
- Flexible for Multiple Sites:
If you frequently relocate your shelter, maintaining a higher wind rating (even up to Region D) ensures it remains compliant. - Suitable for Industrial Use:
Most industrial shelters in Australia are in Terrain Category 2 and may be built to satisfy the n2 wind rating. This includes warehouses and workshops. - Easy to Certify:
Local governments and insurance firms may easily certify buildings that meet this rating.
Final Thoughts
Customising for the Wind Rating of Your Site
Every company and project has their own requirements and uses for their shelter.. That’s why Allshelter suggests that each project should be evaluated on its own merits. Allshelter considers factors such as the wind region, terrain type, and importance level to determine the appropriate N2 wind rating or higher.
General or default shelter designs that do not consider these factors may be a catastrophic failure, non-compliant with the standards, or incur a loss that no firm should risk.
Allshelter Can Help You Build with Confidence
When you work with Allshelter, you’re not only buying a shelter; you’re also investing in a solution designed to withstand the most challenging conditions in Australia. Our team will help you with:
- Location assessment
- Wind region classification
- Terrain and exposure evaluation
- Importance level determination
- Custom design to match n2 wind rating or higher
Engineered to protect your people, equipment, and operations from the weather, Allshelter shelters are built to last.
Do you need help determining the correct wind rating for your area? Get in touch with our staff today to talk to a shelter expert who can help you with every step of the process.
