How to determine your cyclone rating
Updated: Oct 5, 2022
Do you live in a cyclone prone area? Know what cyclone rating you need before you start building.
“Cyclones are powerful weather systems that can cause significant damage to the built and natural environments. They generate severe winds, strong rain, riverine and flash flooding, as well as storm tides. ”
The table below outlines the five cyclone categories and how the Bureau of Meteorology predicts the severity of a cyclone using a five-category system based on the maximum expected gust wind speed at the end of the eye of the cyclone. The wind speed at your home can be different to the wind speeds reported by the Bureau.
Table taken from Cyclone Resilient Building Guidance for Queensland Homes
Wind classifications in cyclone prone areas
Coastal areas north of Bundaberg are classified as Wind Region C. Homes in this area are designed to resist a cyclone with winds of 250 kilometres per hour, which the Bureau of Meteorology classifies as a mid-category four.
Image taken from Cyclone Resilient Building Guidance for Queensland Homes
Homes located on hilltops can experience much higher wind gusts than those on lower lying
flat land. As a general rule, the wind classification is related to the view from the home – the
better the view, the higher the wind classification.
As a general guide, your wind classification can be related to the view from your home
as follows:
No view – usually C1. This classification is used only for homes situated on flat land that is located away from the shoreline and surrounded by many other buildings.
Some view – usually C2. This is the most common classification for homes in cyclone prone areas in Queensland. It is appropriate for homes with a view past the surrounding homes on gently rising ground. It is also used for homes located a street or two away from the coastline.
Good view – usually C3. This classification is used for homes with a view over the surrounding streets or out to sea.
Really great view – at least C4. This is the highest cyclone wind classification and applies to homes built on the tops of hills or on rising land near the coast. An engineer may be required to design all structural elements in these homes.
The wind classification is determined by a trained building professional such as an engineer,
builder or building certifier. The wind classification is used by all designers and construction
trades to select appropriate building components such as roofing, structural connections,
windows or garage doors to resist the wind forces likely to be experienced over the lifetime of
your home.
For more information visit www.qra.qld.gov.au/Resilient-Homes
The above content has been referenced from "Cyclone Resilient Building Guidance for Queensland Homes", provided by © The State of Queensland (Queensland Reconstruction Authority) 2019.