Raising Roof Trusses
Careful preparation and wise use of a crane can allow a good-size roof to be framed and sheathed in a day.
Synopsis: This article deals with getting roof trusses into position quickly and efficiently. With planning and careful preparation, the authors can raise trusses and sheathe a good-sized roof in a single day. Sidebars explain how to make the most of the crane that’s already on site.
We learned truss raising the hard way. Fingers trapped between sliding trusses were broken, and backs were strained muscling 32-ft. wide trusses up two stories for steep-pitched colonial roofs. The process involved six or seven guys and usually lasted a whole frustrating, tiring day. The process was tough on the trusses as well. Lifting them flat would cause the truss plates to bend or pop, ruining the truss. If we were lucky enough to get all of the trusses installed in a day we then faced the arduous task of lugging up all of the sheathing and roofing materials. After all of that hauling and lifting, there wasn’t much enthusiasm or energy for swinging a hammer. Our lives got much simpler after we opened the phone book to the listing for “Cranes.”
We have come to depend on a crane to lift the trusses for all but the smallest single-story roofs. In this article we’ll discuss how we use a crane to assemble simple gable roofs.
Before the roofing materials and trusses are dropped at the site, we anticipate where the crane will be positioned so that all materials are out of the way but still easily within reach. Before the trusses are lifted to the roof, the crane hoists the sheathing, the shingles and the interior-framing materials for the second floor. The crane we hire can usually reach an entire house and garage from one position near the outside middle of the building. We also keep the job site as clean as possible. Scrap lumber and debris can be accidents waiting to happen on raising day. Our scrap pile is always located out of the way but still within tossing distance of the house.
When the trusses arrive, we land them on top of 2x blocks as they come off the truck to keep them as flat and as much out of the dirt as possible. Sometimes trusses arrive as much as a week before they can be installed. If the trusses are not kept flat, they can warp, and after they’ve warped, they’re much harder to install.
Layouts are done with the trusses on the ground
We mark three different sets of layout lines on the trusses before they ever get off the ground. The first set is for positioning the trusses on the walls. The second is for the strapping or furring strips to which we’ll screw the drywall or plasterboard ceilings, and the last set of lines is for the roof sheathing. We also mark the front of the trusses near the tail of the top chord to avoid getting them spun in reverse when they’re lifted. Before we mark these lines, the trusses need to be aligned on top of one another as closely as possible. We arrange them in a stack by tapping them back and forth with a sledgehammer until all of the bottom chords and ridges are in line. When the trusses are in a straight stack, we can make our layout lines.
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