Understanding Wind Load Building Codes for Fabric Structures

Just like any other building, temporary fabric structures must be able to withstand certain environmental factors to ensure the safety of a jobsite or project. This includes seismic activity, snow, weather events, and wind. In particular, wind is a difficult live load to predict, which makes understanding wind load building codes incredibly important.

Just like other buildings, temporary structures can only withstand so much, and design can only take you so far. Despite this, temporary fabric structures are still highly durable and can withstand a myriad of harsh conditions—it’s simply a matter of understanding what your area’s needs are. To help you better understand these codes and how they impact temporary structures, this article will help clarify wind load building codes for temporary fabric structures.

What Is the IBC and What Do They Do?

The International Building Code (IBC) is a council that sets building standards to protect the health and safety of the public. Building designers and construction workers across America look to the IBC’s codes to ensure the safety and structural integrity of buildings. Typically, the IBC updates these codes around once every three years.

While the IBC does set international standards, building codes vary from state to state, including wind load building codes. This is because different areas across America experience different wind events and pressure systems. In fact, these codes can vary by city and municipality as well. This means it is vital to speak with your local building and code administration before beginning a project without the aid of a professional.

What Is Wind Load and Why Are These Codes Important?

Wind load is expressed in pounds; it is the pounds per square foot of wind pressure placed on the exterior of a structure or building. In general, there are three types of loads: vertical, horizontal, and longitudinal. Wind loads are generally horizontal loads with three separate types: uplift, lateral, and shear.

Uplift wind load refers to when the air pressure above the roofing system is lower than the air pressure under the roofing system. This creates an uplift of wind that can pull roofing materials up and off of what they are attached to.

Shear wind load is what can cause a building or structure to tilt, as it expresses the horizontal force that a structure can ultimately endure without cracking or inclining. Lateral wind load is a pull-and-push type of air pressure that can cause a structure to slide off of its foundation and possibly overturn. While shear and lateral loads may sound like the same thing, as they are both horizontal pressure systems, shear loads cause tilting while lateral loads cause sliding.

How Do I Determine Wind Load in My Area?

Fortunately, you don’t have to sit with a calculator to determine wind load and the subsequent codes your building needs to adhere to. The IBC has designated particular wind zones that help engineers determine the loads that will impact the structure and, therefore, the design. The wind zones are as follows, as stated directly in the IBC Wind Resistance Provisions section 6.2.2:

• “Wind Zone 1—130 mph ≤ ultimate design wind speed, Vult < 140 mph.”
• “Wind Zone 2—140 mph ≤ ultimate design wind speed, Vult < 150 mph at greater than one mile (1.6 km) from the coastline. The coastline shall be measured from the mean high water mark.”
• “Wind Zone 3—150 mph (58 m/s) ≤ ultimate design wind speed, Vult ≤ 160 mph (63 m/s), or 140 mph (54 m/s) ≤ ultimate design wind speed, Vult ≤160 mph (63 m/s) and within one mile (1.6 km) of the coastline. The coastline shall be measured from the mean high water mark.”
• “Wind Zone 4— ultimate design wind speed, Vult >160 mph (63 m/s).”

To note, Vult refers to the “ultimate design wind speeds,” or rather, the ultimate load a structure will experience. Additionally, wind load does not account for structures attached to or shielded by another structure, as these factors technically don’t affect or decrease the ultimate design wind speed.

What Factors Should Impact Design?

Because engineers should not rely on the tension and thickness of the fabric to increase the rigidity of a temporary structure, they need to make other considerations. Ultimately, they must consider the structure’s height and shape, as well as its exposure to local windspeed, the classification of the enclosure, average reoccurrence, and geographical features.

Wind load building criteria differ depending on whether the building is 60 feet or higher and dome, flat, hip, gable, or saw-roofed. How much exposure a building receives depends highly on the geographical features surrounding it, such as mountains, valleys, bodies of water, and other surrounding structures. Additionally, the wind speed and how often wind speeds and wind events reoccur will have an effect on how builders should construct temporary structures. Lastly, whether the structure is classified as open, enclosed, or partially open will impact the pressure distribution in a temporary fabric structure.

As you can see, it’s easy to tell why so many states, cities, and municipalities have different codes and regulations for buildings and temporary structures alike. Although potentially overwhelming, the extensive list of variables makes it important to adhere to local codes to ensure safety and stability.

Conclusion: Why Choose Big Top

When you work with Big Top Manufacturing, we don’t just send in our workers and leave. We understand how important it is that your structure adheres to local ordinances, rules, and building regulations. That’s why we’ll provide you with an experienced and adept engineer with the knowledge and resources to ensure your structure meets all the local building codes.

Now that you have a better understanding of wind load building codes for temporary fabric structures, Big Top Manufacturing is here to help you design and build a fabric structure to meet the codes in your area. We can ensure adherence to IBC standards and fully customize your temporary building to meet the specific needs of your project. With us, you can be sure that your jobsite, workers, and wallet are all protected and safeguarded from code violations and environmental factors. For the best jobsite protection, contact Big Top Manufacturing—we’ve got you covered.