If you’re looking into purchasing a portable stage, you’ve probably come across the term “load rating.” What does it mean? Let’s break it down...
What Is a Load Rating?
Load rating means the amount of weight (load) an object will safely support before it fails or becomes unstable. All reputable portable stage manufacturers publish the load ratings for their stage systems. They determine the load ratings by setting up a stage module in a testing facility and putting weight on top of the stage until the structure fails.
An All-Terrain Stage is set up for load rating testing.
The stage is loaded with weights, evenly distributed.
What Is Standard Uniform Load Rating?
The most common load rating spec for portable stages is Standard Uniform Load Rating. Some manufacturers may refer to this as “load bearing capacity” or “weight capacity.”
A standard uniform load is weight that is evenly distributed over the entire surface of an object. The standard uniform load rating of a portable stage is the maximum amount of evenly distributed weight that the stage can safely support.
The standard uniform load rating of a portable stage is the maximum amount of evenly distributed weight that the stage can safely support.
How Is Load Rating Measured?
Standard Uniform Load Rating is measured in pounds per square foot and is usually expressed as “XXX lbs/sq ft.” The higher the standard uniform load rating, the more weight a stage will support.
For example, a Staging 101 4’x8’ Portable Stage Panel (shown above) has a standard uniform load rating of 153 lbs/sq ft. This means the stage panel can safely support up to 153 lbs of evenly distributed weight per square foot of surface area.
Many building codes require a minimum load rating of 150 lbs/sq ft for portable stages, but that number may be higher or lower in some areas - check with your municipality or local fire marshal for more information.
So What’s the Total Capacity of the Stage?
At first glance, the Staging 101 4'x8' Portable Stage Panel’s standard uniform load rating of 153 lbs/sq ft may seem small. But that rating only applies to 1 square foot, and our 4’x8’ stage module is 32 square feet. If we multiply the standard uniform load rating of 153 lbs per square foot x 32 square feet, we find the total uniform weight capacity for the stage panel is 4,896 lbs.
153 lbs/sq ft x 32 sq ft = 4,896 total weight capacity
Whoa, now that number seems really large! So does that mean that that single stage panel can hold 4,800 lbs? Well, yes and no...
Limitations of Standard Uniform Load Ratings
It’s important to note that the test for Standard Uniform Load Rating has some limitations. The weights used during testing are distributed evenly across the entire stage surface, so it doesn’t exactly duplicate real-world use conditions.
Additionally the standard uniform load rating test does not address ‘“dynamic live load’ from having lateral (side to side) movement on the stage, like dance or fitness routines. It also does not take into account “point load,” which is the amount of weight that can be placed on a single point on the stage deck without denting or damaging the stage surface; the most common example where this applies on stage is a grand piano, which concentrates 1/3 of its entire weight on each of its 3 legs.
Also, standard uniform load rating for certain stages may change depending on at what height the stage legs are set. For example, BilJax AS2100 Event Stages have a standard uniform load rating of 125 to 175 lbs/sq ft, depending on platform size and leg height.
The Takeaway on Portable Stage Load Ratings
Standard Uniform Load Rating is an excellent starting point for understanding and comparing the strength of different portable stage options. It’s also an important spec to consider if your local building code has specific load rating requirements for portable stages.
Make sure the stage you choose has a high enough load rating to support the people and equipment you plan to put on it. And if you are planning to put very heavy items like a piano or car on the stage, always consult with the stage manufacturer and/or an engineer to find out if you need to increase the stage’s load capacity through extra parts or reinforcements to ensure your stage can safely handle the load.
Here at StageDrop we sell portable stages with industry-standard uniform load ratings, we work with these products hands-on every day, and we love to talk about this stuff. Contact us today at (609) 971-9200 or sales@stagedrop.com or Request a Free Quote online and we’ll help you find the right portable stage for your needs.