For pitched roofs flat roofs and ceiling joists.
Hip roof span table.
Spacing should be interpreted as the centre to centre distance between adjacent parallel members.
This is based on an article in the journal of light construction.
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.
Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters.
Roof load width rlw and floor load width flw can be determined from as1684 or from the images below.
Surveyors span tables for designing roof rafters.
For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements.
The range of values in the tables provides allowable spans.
If the extension length is half the extension length the 2 hips will meet at the existing wall and the roof will come to a peak with no ridge like half a pyramid.
The roof extension length must be at least twice as long as its width or the 2 hips will meet before they reach the existing building wall.
View joist rafter tables.
Simplified maximum span tables for selected visual and mechanical grades of southern pine lumber in sizes 2 4 thru 2 12.
Column headings refer to live load.
Roof rafter span use this table to determine the maximum lengths of roof rafters based on species and grade of lumber spacing dimensions load and slope.
This chart is for intersections of equal pitch only.
The tables below give maximum spans for rafters and beams.
Floor joist span use this table to determine the maximum lengths of floor joists based on species of lumber joist spacing and joist size.
Additionally compression perpendicular to grain design values f c are included as a consideration for selection of joists and rafters.
Length l in feet is shown at right.
Required size for a given span.
In areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot.
The size of the ridge board and hip and valley rafters is prescribed as are the connections of these members.
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.
Surveyors and structural engineers utilise data from tables below to help calculate the correct size strength and centres of roof timbers for the required spans and loadings.
This chart is for initial rough sizing hip and valley rafters work should be checked by an engineer before plans are finalized.
Limitations which include among others building size roof pitch and design loads the allowed span for conventional rafters can be selected from tables rather than designed through engineering calculations.
