I've heard that trusses can support about 10 lbs per square foot. However, when I stand on them, I weigh 165 lbs with a footprint of about 1.5 inches by 4 inches, which seems to translate to nearly 4,000 lbs per square foot. Can someone explain what I'm getting wrong here?
1 Answer
It looks like you’re mixing up the concepts of uniform load and point loads. Trusses are rated for a uniform load, which means they can handle a distributed weight across a specific area, not just a single weight in one spot. So when you're standing on them, that's considered a point load. As long as the rest of the structure is properly supported, your weight alone won’t break the truss. Just keep in mind that the entire system needs to be installed correctly to maintain its strength.
Thanks for clearing that up! So if I place a 4’x4’ piece of plywood on my trusses spaced 36” apart, and I assume 10 lbs per square foot, I can only expect it to hold about 160 lbs, right?