Wind Load Basics: What You Should Know

If you’ve ever specified or installed a rolling door or grille, you’ve also encountered the term “wind load.” You probably know the wind load requirements for the doors in your facility. You know why wind load requirements are important, but may not be sure on the specifics. Not to worry, we’ll give an overview below to help.

Who Needs to Consider Wind Load?

Everybody! No, just kidding, not exactly everybody. But anyone who is working with buildings and security closures needs to be aware of wind load requirements, what they are, and how they can positively impact and protect buildings (when calculated and used correctly).

What is Wind Load?

As a quick refresher, wind load is the amount of force a rolling door or grille curtain can withstand without pulling out of the guide assemblies or taking a permanent set. It is specified in pounds per square foot (psf).

Where is Wind Load Calculated?

Physically, wind load is calculated in wherever a certified engineer is located – whether that’s in a home or work office.

The more abstract “where” for wind load calculations is anywhere a door or grille will be placed to secure a building’s opening on the exterior of the building. If a leaf could make contact while making its merry way around in the wind, that means your door needs to be wind loaded.

When Do Calculations Need to Be Signed and Sealed?

Wind load calculations must be certified by an engineer in the state where the project will be completed if it's required in the specifications. This may add time and costs to your project and must be recalculated when anything in the list above is changed.

When is Wind Load Calculated?

Wind load requirements for security closures should be calculated during the building's design phase. This way, you and your team can be aware of any special circumstances early and prepare for them.

Why are Wind Load Requirements Important?

The top priority is always safety of building occupants and of the building itself. Building codes are put into place to protect lives and property, and wind load requirements are part of them.

How is Wind Load Calculated?

However, calculating the wind load requirements for your door or grille doesn’t mean wind speed and force are the only factors to take into consideration. When determining requirements, you should remember that all wind loads are transferred to the door guides or wall angles.

This means that the pressure on the guides is a combination of the total door hang weight (dead load) and the wind pressure forces (live load). It’s a combination of everything on and near the door, and the pressure of the wind against it all that goes into the calculation.

Live load forces can far exceed the dead load force on the door, destroying it or causing it to build up a lot of unwanted pressure in your building – and possibly, blowing off the building’s roof!

Remember, you’re not just specifying for maximum wind speed, you’re specifying wind load in pounds per square foot for design load, which also includes factors such as:

• Mean roof height
• Roof slope
• Surrounding topography
• Exposure category
• Directionality factor
• Door area
• Importance factor
• Zone
• Positive or negative pressure
• Internal building pressure

Other considerations for calculating the appropriate wind load for your application are the door type and size that will be installed, what the door will be mounted to and how strong it is, the psf it must withstand (from forces on the door weight, and forces on the curtain, end locks and rivets, wall angles, and anchors), and if you specified for design load or test/ultimate load.

Design load is calculated to a certain number of pounds per square foot, typically with 50% added in as a safety factor. Test/ultimate wind load is the maximum pounds per square foot the door can handle before it is blown out or into the building.

Remember that wind load calculations are not like a blanket that covers all openings in the building; each opening in the facility must be evaluated for wind load.

Is Wind Load Only for Rolling Doors?

Great question! No, wind load requirements are necessary for rolling doors *and* grilles.

If you’re unsure of where to start with wind load requirements for your closures, we can help. Contact us today!

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