Roof Rafter Span Definition

So consider a simple gable roof on a 24 foot wide ranch framed with 2x6 exterior walls and a 1 1 2 ridge. This is the horizontal distance from the inside surface of the supporting wall to the inside surface of the ridge board. Rafter span tables use these tables to determine lengths sizes and spacing of rafters based on a variety of factors such as species load grade spacing and pitch.

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In our sketch above the rafter run is shown as run under the left half of the roof.

Roof rafter span definition.

1 the span of a rafter is not based on the measurement along its length. Definition of rafter run. Rather the span is based on the rafter s horizontal projection. Normally a roof span is the same as the building width between the outer edges of the wall top plates.

Definition of rafter span. 1 in 25 4 mm. Rafter spans for southern yellow pine douglas fir and eastern spruce. Hip rafter angle rafter.

The span would be 11 5 3 4. Also available for the android os. Use this table to determine the maximum lengths of ceiling joists based on species of lumber joist spacing and joist size. The un supported length of the rafter along its slope the diagonal or hypotenuse of a right triangle.

Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. In our sketch above the rafter run is shown as run under the left half of the roof. Span calculator for wood joists and rafters also available for the android os. Every piece is measured cut and fastened together to form the rafter.

The horizontal or level distance covered by the rafter the bottom chord or base of a right triangle. In our sketch the rafter span is referred to as the rafter line length. Live load is weight of furniture wind snow and more. This is the horizontal distance from the inside surface of the supporting wall to the inside surface of the ridge board.

Live load 20 lbs ft 2 956 n m 2. Dead load weight of structure and fixed loads 15 lbs ft 2. The upper rafters in a curb kerb gambrel mansard roof roof. Definition of roof span.

Rather the span is based on the rafter s horizontal projection. Rafter spans can be extended slightly beyond what the rafter tables suggest when there is a cantelever extending beyond the supporting wall. The rafter in the corners of a hip roof. This means that each rafter is built on the job site using dimensional lumber.

The longest rafter on the side of a hip roof in line with the ridge. 1 ft 0 3048 m. Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run. Building with them is known as stick framing.

2 are indicated below. Rafters are the traditional means of framing a roof. 1 psf lb f ft 2 47 88 n m 2. The foot of a hip rafter lands on a dragon beam.