The Impact of Wind Ratings on Metal Building Designs

Regardless of how they’re built, there is no such thing as a wind-proof structure. And while it’s highly unlikely that any building could withstand an E5 tornado or 200 mph wind speeds, pre-engineered metal buildings are specifically designed to stand strong during extreme weather conditions. Unlike their traditional, wooden counterparts that are vulnerable to extreme wind damages, these steel units can keep your property safe and secure for years to come.

High Winds in the United States

There are a large variety of windstorms that occur throughout the U.S. every year, each with characteristics of their own. When designing your ideal steel building, the engineers will need to take the storms in your area into consideration. You can read more about these windstorm types and their possible damages below.

• Straight-line wind – Straight-line wind is the most common wind that occurs today. It earned its name from the way it blows – in a straight line. Their wind speeds can range from very low speeds to very high speeds, its high winds most commonly being associated with low pressure. This wind type can occur most anywhere throughout the nation, no matter its terrain.
• Down-slope wind – This term is often used when describing winds that flow down the slope of a mountain. Down-slope winds with high speeds are a frequent occurrence in both Alaska and Colorado. You may also hear about down-slope winds when referring to mountainous areas throughout the United States, which are also known as special wind regions.
• Thunderstorm – Thunderstorms can form quite rapidly and produce high wind speeds that could damage your personal property, including buildings. It has been found that the U.S. experiences around 10,000 severe thunderstorms each year, most commonly in the spring and summer months. In addition to their extreme winds, they can also create heavy rain, hail, or tornadoes.
• Downburst – Often referred to as microburst, downbursts are powerful wind gusts associated with thunderstorms. Once these bursts reach the ground, they spread across the land horizontally and may even form one or more horizontal vortex rings. Their outflow is typically 6,000-12,000 feet across and 2,000 above. While they do not last very long, they can result in significant damages.
• Northeaster – Depending on the area you live in, you may hear some people refer to these occurrences as nor’easters. They are cold, violent storms that often occur along the northeastern coast of the nation, lasting for several days at a time.
• Hurricane – Hurricanes are severe storms that form over warm oceans, varying from 50 miles wide to 600 miles wide. They have the capability of producing severe winds for several hours at a time, while bringing heavy rainfall to the area it targets. The Saffir-Simpson Hurricane Scale rates the overall intensity of each storm, from Category I to Category V. This type of storm has the highest potential for devastating a large area, affecting a number of people and their homes or businesses.
• Tornado – Tornadoes are violent columns of air that rotate continuously, extending from the ground to the base of a thunderstorm. Like hurricanes, a tornado’s intensity is measured by the Fujita scale, ranging from an F0 to an F5. While high winds are a typical way to determine when a tornado is coming to your area, the winds associated with these storms can destroy homes, office buildings and many other structures. Tornadoes are known for causing the highest number of wind-related deaths in the United States each year.

Metal Building Construction Based on Wind Ratings

Traditional construction projects that were completed using wooden materials aren’t as durable, reliable or sustainable as our pre-engineered metal buildings. Not only are they susceptible to wood rot and termites, but they aren’t made to stand strong against windstorms and driving rain. Our steel structures are made with the finest galvanized steel materials available today, allowing them to withstand extreme weather conditions. Though we cannot guarantee your building will remain standing during storms such as hurricanes or tornadoes, they can be designed to withstand higher than normal wind and snow loads.

Exposure Ratings for Prefab Steel Buildings

The exposure ratings of a steel structure indicate the threat level of wind loads in certain regions of the country. This also includes the overall impact of urbanization. If you aren’t too sure what these exposure ratings are, we’ve listed more information below to help you better understand.

• Exposure B – This rating is generally used in urban, suburban, or wooded areas that have a variety of windbreaks such as buildings and homes that are close together.
• Exposure C – Exposure C wind ratings are for open, rural areas that have very few buildings or hills that are under a height of 30 feet. With such a lack of windbreaks, it’s required to have an appropriate design for wind loads in your area.
• Exposure D – These are assigned to flat pieces of land that have no windbreaks at all. With no structures in place to block wind flow, windstorms could be a frequent occurrence.

Having your structure designed to withstand certain wind and snow loads in your area is crucial if you often experience storms and high winds. While it may not be your complete responsibility to design a metal building suited to those wind loads, it is important that you understand every aspect of the process. If you continue to have questions or concerns after reading this article, feel free to contact one of our building representatives at +1 (800) 691-5221.