12 Inches at a Time: Why Spacing and Bracing Matter
Let’s talk about something that doesn’t always get the spotlight it deserves: temporary truss bracing. If you’re setting trusses and want to avoid disaster, this is something you absolutely need to understand.
The Domino Effect
Think about a truss like a domino. It’s tall, it’s lightweight, and it’s narrow. That means it’s naturally unstable. Line a few of them up without bracing, and all it takes is one gust of wind or a bump from a worker to bring the whole system down. It’s not just about the materials at risk, it’s about keeping workers safe. That’s why we install temporary bracing as we go. It keeps the trusses upright, in line, and ready for the rest of the build.
Types of Bracing to Keep Everything in Place
A typical truss has multiple planes that all need to stay rigid. That’s where different types of temporary bracing come in.
The top chord bracing ties all the trusses together across the roof. Bottom chord bracing keeps things stable at the ceiling level. And then there’s web bracing, which often includes diagonal members to distribute load and resist buckling. For flat trusses especially, this kind of bracing is crucial to keep everything from collapsing under its weight, before you even add roofing material or workers walking on them.
The Right Way to Brace
There’s a common shortcut in the field: people stand the trusses up and then throw in some bracing perpendicular to the trusses. But that’s not enough. The Truss Plate Institute and Structural Building Components Association recommend diagonal bracing as well, to keep the whole system from shifting or buckling.
Here’s a smarter approach: place your bracing on the underside of the top chord or on top of the bottom chord. That way, when you go to sheath the roof or ceiling, the bracing can stay right where it is. No need to remove it.
Start at the End Wall
Begin with the gable end truss. That very first truss needs to be solidly braced down to the ground so you’ve got a stable start. That brace can go to the ground inside or outside of the building. As each additional truss is added, brace it to the one before it and continue adding roof sheathing or more diagonal bracing as you go. This step-by-step method keeps everything locked in as you move down the line.
What to Do (And What Not to Do)
Let’s start with the dos. Brace that first truss before anything else. Use quality materials: 2x lumber and the right size nails or fasteners, as recommended by the Building Component Safety Information. Follow the engineer’s guidance, especially for long spans over 60 feet. Below that, BCSI guidelines are usually sufficient.
Now the don’ts. Never walk on unbraced trusses. Even stepping on the bottom chord can create enough pressure to buckle the top chord and bring the whole truss down. Don’t use damaged or undersized lumber. Never use what we call “suicide blocks”, those short blocks that only tie one truss to the next. They don’t provide the triangulated support you need, and if one truss falls, they all fall.
Another big no: don’t remove temporary bracing before the permanent bracing is installed. If you’ve braced underneath the top chord or on top of the bottom chord like we talked about earlier, you won’t need to. You can sheath right over it and leave the bracing in place.
The Dreaded S-Shape
When trusses aren’t braced properly, they can start to fail under their weight. One of the first signs is what we call “essing.” It looks just like it sounds: the top chord starts to bow and sag, making an S-curve. From underneath, you’ll notice the bottom chord is still straight, but the top looks like it’s waving. That’s a major red flag. If you see it, stop immediately, clear out the building, and get professional help to stabilize the structure.
Timing is Everything
Bracing should begin with the very first truss. Once it’s locked in, each truss that follows needs to be braced right away. Don’t wait until the end. After several trusses are up, start adding your diagonal bracing to lock the whole system together and prevent buckling. Once a few trusses are in place, you can begin sheathing the roof. As long as your temporary bracing is on the underside of the top chord, you’re good to go.
Don’t Let the Weekend Wreck Your Work
I can’t count how many Monday mornings start with a call from a contractor saying, “We put the trusses up Friday and left them for the weekend. A wind came through, and now they’re all on the ground.” It’s preventable. No matter how rushed you are or how badly you want to wrap up the week, take the time to brace things properly before you walk away. You’ll be glad you did when you return to a clean, standing structure instead of a costly mess.
Recipe for a Safe Install
Start with a bracing plan. That can come from your engineer or the BCSI guidelines. Make sure your crew is trained, and everyone understands the process. Have your materials ready ahead of time so you’re not tempted to cut corners. And keep inspecting as you go. Watch how the trusses and bracing perform under their weight.
If you follow the recommendations, whether from the engineer, the BCSI, or your truss manufacturer, you’ll end up with a safe, accurate installation. That’s the goal every time. Get the bracing right, and you’ll be set for the next step.