Explaining Wind Uplift Ratings for Metal Buildings

For generations, wood was the standard material used to create buildings. And while there are still many wooden buildings being constructed, recent years have seen an explosion in the popularity of metal structures. With cost advantages and impressive design flexibility, there is a lot to like about building with metal.

But is a metal building sturdy enough to stand up to the elements? Some potential buyers worry about the durability and structural integrity of a metal building, since it is lighter than a building of the same size made from wood. Of course, at Carport Kingdom, we specialize in metal buildings and we know just how strong they can be. With this article, we’d like to talk specifically about wind uplift and how this potential issue can be addressed.

Understanding Wind Uplift

As you might be able to guess from the name, wind uplift is when wind causes upward forces to be exerted on a building. This phenomenon has the potential to occur when wind is able to pass both under and over a structure – as would be the case with an open-sided carport. It’s also possible that a building with large eaves could experience significant uplift. Powerful uplift could cause the roof to come off, and even if that does not happen, serious damage could be sustained that would leave the building unsafe for use.

What Causes Wind Uplift?

Not every building is at a particularly large risk for wind uplift. For example, a structure in an area that is unlikely to experience strong winds will have little to worry about. So, when building a metal structure in a protected area, uplift ratings won’t be much of a concern. In addition, buildings that are low to the ground won’t experience as much wind uplift compared to taller structures.

The design of the building is also going to have a lot to say about wind uplift forces. If your building is completely enclosed – like it would be with a metal garage from Carport Kingdom – it’s going to be hard for serious upward forces to develop because the wind won’t be rushing under the building. However, if you have a garage with large, open doors, or a carport with no sidewalls at all, uplift could be a concern.

Determining Wind Uplift Ratings

To determine wind uplift ratings, there are several tests to perform on the metal to determine what class a roof is.

The first test is the most common: the UL-850. This test involves subjecting a 10’x10’ piece of the building’s roof to constant uplift pressure for 5 minutes, then subjecting it to oscillating pressure for one hour. It’s the roof’s response to the oscillating pressure that determines the class of the roof. The three common classes are 30, 60, and 90.

• Class 30.The roof withstands a constant pressure of 30 psf, and oscillating pressures between 22 and 42 psf
• Class 60. The roof withstands a constant pressure of 60 psf, and oscillating pressures between 44 and 83 psf
• Class 90.The roof withstands a constant pressure of 90 psf, and oscillating pressures between 66 and 90 psf

There are several other tests that are used to determine the strength of the metal and how much pressure it can withstand before failing. These tests include the ASTM E 1592, and the ASCE 7-16. The FM Global Standard 4471 test and the UL 1897 tests are used to make sure the metal and the structure complies with insurance standards and residential codes to ensure that the building is stable and durable.

Trust Our Engineers

When you work with Carport Kingdom, you’ll have access to our expertise and we’ll help you understand what you should be looking for in a new metal building. We can work with you to discuss the realities of your property and what wind conditions you may experience – and how that should impact your design.

Explore our Build & Price tool to design and customize the perfect carport, barn, or shed. This tool lets you experiment with design choices and various features, but you are also welcome to contact us if you need direct assistance.