Roof trusses arrive at the job site ready for installation. The truss manufacturer specifies exactly how each truss must be mounted. The typical roof truss rests on the top wall plates, but if you’re building a hip roof or if the roof has directional changes, the ends of some trusses will butt into support beams or girder trusses. When a truss connects to a vertical plane instead of sitting on a wall plate, a truss hanger is necessary. The truss manufacturer will send the truss hangers along with the trusses.
Things You'll Need
- Truss diagram
- Truss hangers
- 1 1/2-inch shank nails
- Tape measure
Familiarize yourself with the truss diagram that accompanies the delivery of the roof trusses. The diagram will designate the position of each truss with a number, such as T-1, T-2 and T-3. Each wood truss will bear a corresponding number, indicating its position in the layout.
Install the girder trusses first and set the roof trusses that will rest on the wall plates. This will generally be the bulk of the truss system, and these are known as the common trusses.
Locate the position on the side of the bottom chord of the girder truss where the truss hangers will attach. This will coincide with the intersection of trusses at a point where the wood members in the roof change direction. Make a pencil mark on the girder truss that matches the measurement on the truss diagram.
Position the truss hanger with the open end at the top. A truss hanger is a metal “sling” that supports the base of another truss. The bottom end is cupped. The back sides of the hanger have metal nailing flanges that attach to the girder truss; the sides of the cupped part of the hanger serves as a nailing flange to secure the end of the new truss.
Align the bottom of the truss hanger with the bottom of the girder truss and make sure the hanger is straight.
Insert nails through the holes in the nailing flange and into the girder truss. Nail only through the predrilled holes. Standard nails for attaching truss hangers are 1 1/2-inch shank nails, but check the truss specs and use only the type of nails called for.
Slip the end of the adjoining truss into the metal sling of the truss hanger. Check the truss manufacturer’s specifications at this point to determine if you must butt the new truss snugly against the back of the truss hanger, or if you should leave a 1/8-inch space between the two.
Insert shank nails in the side holes of the nailing flange to stabilize the new truss. Install additional truss hangers and trusses in the same manner.
Tips & Warnings
- Not all roof trusses require hangers. If you have a simple gable roof, all the trusses will install directly on the wall plates.
- Do not nail or otherwise attach the roof trusses to each other or to the wall plates anywhere other than where the manufacturer specifies. To do so can void the warranty on the trusses.
- Photo Credit John Foxx/Stockbyte/Getty Images
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