Making the Case for T-Bracing Trusses
Originally published by: Construction Magazine — May 10, 2016
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Building failures often start at the top. A strong truss ensures for a stronger building, adaptable to the rigorous winds and rumblings of nature.
One method worth considering as today’s buildings grow bigger and more complex is T-bracing (or T-reinforcement).
An advocate for T-bracing is David Brakeman, engineering director and vice president for Alpine, an ITW Company; member of the Truss Plate Institute; and a 2016 inductee of the Rural Builder Hall of Fame. He believes post-frame builders in particular should consider its use as part of the permanent bracing system as an alternative to the conventional lateral and diagonal bracing system.
He starts with a brief description of the conventional system.
Figure 3: T- and I-Reinforcement (figure B3-21 from BCSI booklet)
“Some parts of the truss are long and slender, and if that’s a compression member, it can buckle if not held in place. What we find in post frame is what we call the lateral bracing, bracing that would run perpendicular to the trusses in the web,” he said.
If done correctly, diagonal bracing is used in conjunction with lateral bracing to complete the job to help stabilize the forces that accumulate.
The use of permanent lateral and diagonal bracing is correct, but Brakeman thinks T-bracing offers added advantages in terms of safety and manpower, and at a lesser expense.
“Instead of running those laterals and diagonals, that have to be installed after the trusses are all up and in place, you can reinforce those members by nailing on a T-brace,” Brakeman explains. He goes on to describe the process.
“For example, if the web is a 2×4, you would take another 2×4 the same length as that web, and nail it on the side, so the cross section would look like a T.”
The advantage? Brakeman says it doesn’t take any more material to do that because you’re eliminating all the laterals and diagonals. “Instead, you’re using that same material to put on these T-braces and you can do that on the ground before you lift the truss. So you save a lot of labor on guys having to climb through trusses up in the air, and it’s a lot safer.”
Brakeman would like to see all post-frame builders using the T-bracing system and he will continue to advocate for its use. While his own experience with post-frame builders supports his comment that most are very good at building strong, safe buildings, he knows that not all of today’s newer, long-span buildings are given an equal opportunity to survive.
“When we get substantial snowfalls, there’s going to be buildings that have been built within the last few years that will be tested,” he predicted.
Of particular concern are wide-span buildings, often used for animal confinement, with large, long corridors.
“They’re wide buildings, 100 foot or 200 foot wide, and that’s more than what can be spanned with one truss,” he said, “so you have two half-trusses butting back-to-back and meeting in the middle. If those aren’t braced well, they’ll buckle. You don’t even have to get the design load on it to have a problem when the bracing is incomplete.
“Any post-frame builder who has been around a few years knows about this issue,” he continued. “In the northern tier of the United States it’s pretty well known. But a solution is the use of the T-bracing technique, so if your crew doesn’t get all the laterals and diagonals in all the right places, T-bracing is a more effective way to do it, and at a lower cost.”
Can T-bracing be used for other types of construction? Brakeman said, “Yes! It’s a good alternative for many roof truss-framing situations in any type of building, but it’s particularly good in post-frame construction because the trusses are almost always placed at a 4 foot on center or greater and this makes it harder to install the lateral and diagonal type of bracing.”
For a more technical explanation of the T-bracing method, read this article provided by the Structural Building Components Association.