I’ve done a lot of framing in my life, but nothing gets my juices flowing like a good truss set. To me, it’s kind of like drinking a case of Five Hour Energy drinks, a hot date with a super model, and shooting a machine gun from the back of a drag car all at the same time. I’m super excited, nervous and scared to death that my heart is going to explode out of my chest. But unless you’re an adrenaline junky like me, a truss set can be a dangerous Tim Burton-esque nightmare that could potentially kill you. Whether you’re a seasoned framing pro or you’re a truss building newbie, you’ll be sure to benefit from these tips for a safe and secure truss set.
To Crane or Not to Crane – That is the Question
There’s one thing that’s the same when it comes to trusses; them son of a b’s are heavy! No matter what size trusses you plan on setting, don’t expect to install them without some serious help. Dudes whose fingers can easily fit all the way around a soda can, men who eat a sandwich with one bite and fellows whose voices are as deep as a well are probably a good fit for lifting trusses by hand.
Once you price a crane rental ($150+ per hour with a 3 hour minimum) you can see how opting out to hire a bunch of grunts to set trusses can be something you might be interested in. But don’t think that saving a few bucks is in your best interests. Any roof truss that’s over 30’ long and has a pitch greater than 5/12 is probably too big to be lifting by hand. Not only is it really heavy, it’s going to be too wobbly to safely set by hand – get a crane.
Prepping the Trusses
Once your trusses are delivered, you’ll need to prep them for setting by hand or the crane. More than likely, that means lots of moving and heavy lifting. All pre-manufactured truss sets come with a truss layout plan. Trusses are labeled both numerically and alphabetically. A truss layout tends to resemble a jigsaw puzzle that’s all the same color and shapes, and can be hard to decipher.
Because truss sets move from one end of the house to the other, you’ll need to pick a side to start the set. Typically, you’ll want to start the truss set on the farthest side of the house or the opposite end of where the crane will set up. Unfortunately, when trusses are assembled at the factory, the guys who stack them up are probably smoking crack and there really is no rhyme or reason to the way they are stacked when delivered. This often means you’ll be flipping the entire stack, flipping every other truss or digging your way down to the very bottom just to get the trusses you need to start the set.
The most important trusses in a truss set always seem to end up in the middle or bottom of the stack. Before you begin a truss set, you’ll need to secure:
- Gable Ends-
You’ll need to get these out of the stack to hand set them or to sheet them with plywood for when the crane arrives. Don’t forget to cutout a small triangle space at the top of the gables webbing to allow the cranes hook to hold the truss during the set.
- Hip Girder-
These trusses are used for a hip roofing system. They need to be set by hand first so the hip jacks can be attached. These trusses help provide a secure foundation for the other trusses during the remainder of the set. Many builders assemble (and brace the crap out of) these trusses on the ground as a whole to allow the crane to lift the entire set in one shot.
Trusses like these support the weight of other trusses where no bearing wall is in place. Typically, two or more trusses are nailed together and metal buckets are attached on a 2’ layout.
When trusses are too wide (tall) to drive on the highway, they need to be cut down to the appropriate width. Piggybacks are attached to the tops of the shortened trusses to achieve the final height and pitch. These go on last and should be set aside.
- Crotch Flipper-
I really don’t know what else to call this easy to make truss setting tool, but I like to say crotch flipper. It’s basically a 2×4 with a 6-8 inch “V” shaped crotch cut into the end. It’s used to safely handle and flip trusses by hand.
These 1×3 wooden strips are used to hold the trusses temporarily in place on a 24” layout. I like to cut these at 30” so the ends don’t split once you nail them in place. Layout the strips on 24” and tack two 8d nails on each end. This way they are ready to go once you’re ready to set the trusses. Some people like to use manufactured metal spacers, but I prefer good old wood. When trusses aren’t on a 24’ layout, you can easily adjust a wood strip unlike metal braces.
- Gable Bracing-
Gable ends need multiple braces to hold them in place. Since they are balanced precariously by themselves, a 2×4 vertical T-brace and a 2×4 diagonal brace are needed before the truss set begins. Place one in the center and one every 4-6 feet off of each side of the gable end. Set these on the outside of the building and stake the ends into the ground or else your bracing might be in the way of the other trusses.
- Bearing Wall Bracing-
Be sure your bearing walls are secured and leveled with plenty of 2×4 bracing to ensure it’s in the right place for the truss set.
- Temporary Bracing-
You’ll also need plenty of 1×4’s for diagonal bracing once you’ve got a few trusses set. This prevents the dangerous sway that many trusses exhibit when they are temporarily attached with just stay-lathe striping.
There are a million safety rules and regulations associated with setting trusses. So much in fact, that I could sit here and write about them all day and still not even scratch the surface. The tips here should be considered a general overview, but be sure to consult your own local rules and best practices. If you’re up for some light reading (115 pages) about truss safety, I recommend glancing though the Structural Building Components Associations (SBCA) and Truss Plate Institutes (TPI) guide to good handling, installing, restraining and bracing of metal plate connected wood trusses that can be found here. In most cases, you’ll get an abbreviated version of this guide with your trusses. While most of the instructions are severe overkill, it’s really important to be as safe as possible when handling and setting trusses. Stay safe and good setting!