Roof Joist Angle Span

Rafter and joist span faq.

Roof joist angle span.

This is based upon the span of the rafter horizontal span not total rafter length live and dead loads. Pitch this is the incline of the roof expressed as a fraction. For a gothic style the rafters must equal the span 60 while an elizabethan style requires the rafters to be longer than the span. If you add an eaves overhang dimension then the amount the rafter sticks passed the wall will be added to the rafter length.

More roof calculators roof truss calculator how to cut rafters. Lh and dlh series joists are for longer span conditions and are capable of supporting larger loads. 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. Includes result for hip valley factor slope factor and the roof slope in degrees. 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.

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. Span calculator for wood joists and rafters also available for the android os. In making your choice consider how you will insulate your insulate your roof. 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.

This rafter span calculator is species specific for douglas fir hemlock etc. 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. Another option are 2 x 8 rafters spaced 24 inches o c. The lengths and sizes of joists vary depending on the species and quality of the lumber used.