Nearly all roofs are framed using one of two methods: standard stick framing or newer truss framing.

Stick-framed roofs (shown at right) utilize individual rafters that span from the top of exterior walls to the ridge.

Truss-framed roofs are built from triangular-shaped, pre-made truss units.

Gable and hip roofs may be built primarily of trusses; other roof shapes, particularly those with dormers or on houses with cathedral ceilings, attic rooms or attic storage areas are stick built. Stick framing creates a triangle between rafters and ceiling joists. Collar beam adds strength at the middle.

Like wall studs and floor joists, rafters and trusses are spaced every 16 or 24 inches from center to center. Most roofs utilize 16-inch spacings for strength and rigidity. Rafters are usually positioned directly above wall studs.

A truss (shown below) is one contiguous double rafter/ ceiling joist unit. Truss construction is just as strong but is lighter weight and uses smaller sizes of lumber than stick framing.

Because trusses are carefully engineered units that shouldn't be cut, they are not a good choice for roofs that may be modified at a later date. And because they have several intermediate support members, they don't allow use of the attic space.

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