Roof Joist Angle Span

The table states that 2 x 6 rafters spaced 16 inches on center o c can span a maximum distance of 13 feet 5 inches.

Roof joist angle span.

The lengths and sizes of joists vary depending on the species and quality of the lumber used. Kcs joists are a version of the k series joists but designed for a constant shear and moment which allows for greater flexibility for locating extra loads such as those from rooftop units. For example you can span a 1 grade no knots southern yellow pine a greater distance than a 2 grade with knots southern yellow pine. Includes result for hip valley factor slope factor and the roof slope in degrees.

For a gothic style the rafters must equal the span 60 while an elizabethan style requires the rafters to be longer than the span. In making your choice consider how you will insulate your insulate your roof. This rafter span calculator is species specific for douglas fir hemlock etc. Pitch this is the incline of the roof expressed as a fraction.

Roof angle 1 1 5 2 2 5 3 3 5 4 4 5 5 5 5 6 6 5 7 7 5 8 8 5 9 9 5 10 10 5 11 11 5 12 12 5 13 13 5 14 14 15 5 15 5 16 16 5 17. Rafter and joist span faq. Another option are 2 x 8 rafters spaced 24 inches o c. While pitch and slope are used interchangeably they are not the same span also known as gable width this is based on the total footprint of the house and refers to the distance between two exterior walls.

For example in the rafter span table below the highlighted cell in the 40 live load table indicates that 2 x 8 southern yellow pine joists that have a grade of 2 that are spaced 24 apart can have a maximum span of 10 feet 3 inches 10 3 if designing for a live load of 40 lbs ft 2. This is based upon the span of the rafter horizontal span not total rafter length live and dead loads. More roof calculators roof truss calculator how to cut rafters. Also available for the android os.

Calculate the length of a rafter from the roof slope ratio of inches per foot and a building width measurement. In snowy areas your roof should be at least 10 12 40 to allow snow to shed while the safest roof pitch in very windy areas is between 4 12 6 12 18 5 26 5. These joists are typically used in roof structures. To size joists and rafters use the maximum span tables for southern yellow pine.