Wind speeds vary from region to region and are also affected by your local terrain and building importance level. By making sure that the retailers or contractors you are looking at buying a shed from know the site specific location that you intend to have the shed built you can ensure that you are getting a shed that is engineered for your site conditions.
This is another reason why it’s a good idea to buy local from accredited shed dealers who understand your needs and who engage engineers to look at each and every shed ordered to ensure that the engineering is adequate.
Here’s a couple of simplified examples how region and terrain effects wind speed requirments for sheds. For this example we will use Importance Level 2 sheds.
For example region A windspeed is 45 m/s (metres per second) then the terrain for the site in region A is applied to the windspeed. A shed in a suburban back yard which is shielded by surrounding homes and sheds would meet A3 (region A , terrain 3). For an importance level 2 shed , Windspeed for A3 is 32 m/s so you can see that the sheltered location has lowered the windspeed and as such, the required engineering for your shed.
Region B windpseed is 57 m/s , Then your terrain is applied , lets say your on a rural residential block of a few acres that is reasonably sheltered (not on a cleared hill) and your shed is reasonably close to the house giving you a terrain catagory of 2.5 giving you a wind speed of 47 m/s . Your shed should have engineering that covers at least 47 m/s. for an importance level 2 building.
Below is a chart from the Australian Steel Institute and ShedSafe that lists some more examples. Always check with your council or certifier or licenced builder to make sure you are going to purchase a shed that is correct for site.