Roofing 3 - Ordering Trusses

Ordering the Trusses

Roof framing ranges from the simplicity of prefabricated roof trusses to the complexity of cutting and assembling a complex roof design from scratch. This article will cover only the basic truss construction as this is the recommended procedure for novice builders. Roof trusses are a pre-built series of structural members designed to carry the load of the roof to the outside walls.

The structural members are most often 2 x 4's or 2 x 6's. Trusses are ordered through your supply store and built in special factories to your individual specifications; however, home centers and building supply companies stock the standard sizes for most garages. garage kits usually provide the necessary trusses. If you've made some alterations to your roof line, you may need to special order them. Check with your supplier first to see if they have a special truck that can deliver and place the trusses on top of the walls. They may even have a crane truck that can gently lift the trusses and set them in place.

Usually the supplier can deliver everything needed for a roof frame in truss form. If, however, you have a more custom roof line, you may need to build all or part of the frame yourself. Building your own roof frame is also well within reason for the novice although we would advise consulting with local professionals and more detailed carpentry books for more information on rafters. If you plan to heat the garage and insulation is to be placed between the rafters, the space must be wide enough to provide for the thickness of the insulation. Rafters are placed at 12, 16, or 24 inch intervals. Check your local building code. The size, spacing and span of the roof rafters must be coordinated to effectively carry a given load weight for your area. This load includes such factors as roofing materials and snow or ice accumulation.

Most Common Mistakes:

    1. Ordering inaccurate trusses.

  1. Neglecting to inspect the trusses upon arrival at the building site.


Your roof plans should include the following information to aid you when ordering the roof trusses:

    1. Slope

    1. Size of rafters

    1. Spacing of rafters

    1. Length of overhang

    1. Location and size of ceiling joists

    1. Size of ridge beam and any other bearing beams

  1. Load Weight