At some point during a remodel, you arrive at the math. It’s when you’re standing on an area that used to have a wall there. And now you can picture a hole in the room that must get filled. And then gravity becomes your deadline.
Now you have to learn about span charts for engineered beams. They is not a grid of numbers. They convert weight of your floor into strength of the piece of wood supporting it. Most homeowners look at a beam and see a stick. For engineers, it’s a lever arm resisting tension and compression. A chart explain how various ratings for stiffness and depth prevent the lever from breaking. No, you don’t have to be an engineer to read one. But you do have to grasp the reason for its columns.
How to Read Beam Span Charts
Engineered wood is not created equal. The chart shows differences between LSL, PSL and LVL. For residential applications, LVL is what is used most commonaly for floor beams and headers. It is consistent because it consists of a series of thin veneer sheets glued together. PSL are stronger, require fewer members than LVL and handle huge span uses. LSL is the economical version of engineered lumber and good for short runs and rim boards.
Selecting the appropriate family of engineered wood matter, you don’t want to overpay for PSL capacity when all your application requires is LVL strength. The chart will help identify the proper product for the task so you don’t buy something that “looked familiar” or was cheapest and ended up being the wrong material.
The main thing you use to control the span is the depth. As the guide shows, making the beam deeper lets it supports more without drooping. A 5.5-inch depth may work for a short header. A 14- or even 16-inch deep beam would probably be needed for a 20 foot span. These depths are what allow more loads. You can see that in the chart. They also introduce the concept of E-values. The E stands for modulus of elasticity. The higher the number, the stiffer the beam. Stiffness governs how much bounce the floor have under foot traffic. A 1.8E beam will be lively while a 2.0E beam will be solid. And that little bit will make all the difference between a cheap and a durable floor.
Another important detail is multi-ply construction. Stack up two or more of those in place of a single beam. And don’t think you can simply “cordwood” them; stacking them directly onto each other. Fasten the plies with appropriate bolt or nail pattern. Otherwise they’ll slide relative to one another and reduce their capacity.
These fatter packs require greater bearing lengths (listed on the chart). Make sure there’s enough width of seat in the supporting post or wall to avoid crushing. One of the most common inspection failures is having a beam that’s too long for its bearing plate. Eventually it will dig into the underlying wood and sagged. Check the minimum bearing length for your particular support condition.
Hangers are the weak link in most DIY beam installations. They use the wrong type of hanger, which is the weakest part of the system. If your hanger doesn’t match the size of the beam (depth and width), then your big ass beam won’t hold. You should of used better hardware.
The guide stresses using the right type of hanger, which means matching its model number to the beam’s depth and width. Top flange hangers rest on top of the supporting structure while face mount hangers rests against the face of the joist where it meets the header. Consider reaction loads and use the correct fastener.
Don’t guess; don’t skimp. Don’t take a chance. Check the manufacturer table. Check that the beam has an E-grade stamp. Make sure it says how many plies it is made of. Those little things matter when the house settles.
By the time you see cracks in the drywall, the damage is already done. Save yourself the headache by planning ahead with these charts. Treat it like backbone and it will hold everything else up.
