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To determine the number of trusses you need, measure the full length of the roof ridge, convert that length to inches, and divide by 24 (the standard on-center spacing). Always round up to give the structure full support and add a few extras for overhangs or complex rooflines. This approach keeps your roof strong and code-compliant.

Start by measuring the span—the full width of the roof’s underside—then note the pitch, or how many inches the roof rises for every 12-inch run. Accurate span and pitch numbers help your supplier size each truss correctly, saving lumber and ensuring the roof performs as it should. Your roofing pro will be able to provide accurate measurements for you.

A three-person crew with the right lifting equipment can set a full set of trusses in a single day. Complex roof shapes or limited crane access can stretch that timeline, so talk with your roofer about the schedule and whether you’ll need to stay elsewhere during installation. Careful planning keeps the job safe and on target.

Trusses are prefabricated off-site, arrive ready to lift into place, and install faster and more consistently than site-built rafters. Rafters are custom-cut on-site by skilled carpenters, so they take longer and cost more in labor. Knowing the trade-offs—speed and uniformity versus on-site customization—helps you pick the best framing method for your roof.

If you’re not a licensed roofer, hire a pro. Installing trusses requires heavy equipment, safety gear, and code knowledge that most DIYers lack. While doing it yourself might trim labor costs, one mis-set truss can lead to expensive repairs or voided warranties. A certified contractor installs trusses quickly, follows code, and protects your home’s value.