When you shop for a patio or carport kit, you'll see ratings like N2, N3 or C2. These are wind ratings, and they're one of the most important parts of your kit. They tell you how much wind the structure has been engineered to handle. Here's what they mean and how to make sure you order the right one.
Please note: this blog is a general guide only. Your kit is engineered for the wind rating you select, so it's important to confirm the correct rating for your site before you order. If you're not sure, check with your certifier or builder, or call our office on 1300 156 381 and we'll help you work it out.
What is a wind rating?
A wind rating (also called a wind classification) describes how strong the wind can get at a particular site. In Australia, wind classifications for houses and small structures are set out in the Australian Standard AS 4055. Every patio and carport has to be engineered for the wind rating of the site where it's built.
Wind doesn't just push on a roof. It also lifts it. A patio roof has to be strong enough, and fixed down well enough, to stay put in the strongest winds expected in your area. That's why the rating affects the size of the beams, the number of posts, the footings and the fixings.
N ratings and C ratings
- N ratings (N1 to N6) are for non-cyclonic areas, which covers most of Australia. N1 is the lowest wind speed and N6 the highest.
- C ratings (C1 to C4) are for cyclonic areas, mainly the northern coastal parts of Australia. C1 is the lowest and C4 the highest.
The higher the number, the stronger the wind the structure has to handle, and the stronger the kit needs to be.
What decides your wind rating?
Two houses in the same suburb can have different wind ratings. The rating depends on four main things:
- Wind region: Australia is divided into regions. Regions A and B are non-cyclonic, and regions C and D are cyclonic.
- Terrain: an open, exposed site, such as near the coast or open paddocks, gets more wind than a site in a built-up suburb.
- Shielding: surrounding houses and buildings can shelter your site from the wind.
- Topography: homes on hills, ridges or steep slopes get stronger winds than homes on flat ground.
How do I find my wind rating?
There are a few ways to find out:
- Check your house plans or building approval documents. The wind classification for your home is often listed there.
- Ask your certifier or builder. They work with wind ratings all the time.
- Contact your local council. Some councils can tell you the wind rating for your area.
- Ask an engineer for a site-specific assessment, especially if your site is exposed or on a hill.
Your kit is engineered for the wind rating you select, so please confirm the right rating for your site before you order. If you're unsure, give our office a call on 1300 156 381. It's much easier to get it right at the start than to change it later.
Why the right wind rating matters
- Safety: a patio or carport that's under-rated for its site could be damaged, or cause damage, in a storm.
- Approval: your certifier will check that the structure is engineered for your site's wind rating.
- Peace of mind: knowing your roof is built for the conditions means you can relax when the next storm rolls through. Read more in our storm season guide.
Your kit must be rated for at least the wind rating of your site. A higher rating is fine; a lower one is not.
Walls change the wind loads too
If you close in one or more sides of your patio, the wind acts on the structure differently, and the roof has to be engineered to suit. If you plan to enclose any sides, now or down the track, call our office on 1300 156 381 before you order so we can talk you through what's needed. Our insulated wall panels guide explains more.
Wind ratings on our kits
The wind rating for each of our kits is listed on its product page, and the price shown is for that rating. If you need a different wind rating, contact our office on 1300 156 381 or at orders@onlinepatios.com.au and we'll quote the right kit for your site. Our Carport Specials include both non-cyclonic kits rated up to N2 and cyclonic kits rated up to C2.
Each kit is engineered for the wind rating shown. An incorrect wind rating may mean your structure isn't suitable for your site and may not be approved.
Every kit comes with engineering for its wind rating, which you'll need for your approval. See our council approval guide for the next step.