For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements.
Hip roof span table.
Column headings refer to live load.
Roof load width rlw and floor load width flw can be determined from as1684 or from the images below.
Additionally compression perpendicular to grain design values f c are included as a consideration for selection of joists and rafters.
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.
For pitched roofs flat roofs and ceiling joists.
Simplified maximum span tables for selected visual and mechanical grades of southern pine lumber in sizes 2 4 thru 2 12.
Floor joist span use this table to determine the maximum lengths of floor joists based on species of lumber joist spacing and joist size.
In areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot.
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.
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.
Hese span tables for joists and rafters are calculated t on the basis of a series of modulus of elasticity e and bending design values f b.
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.
Surveyors span tables for designing roof rafters.
View joist rafter tables.
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 is based on an article in the journal of light construction.
Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters.
Spacing should be interpreted as the centre to centre distance between adjacent parallel members.
The range of values in the tables provides allowable spans.
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.
Length l in feet is shown at right.
Required size for a given span.
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.
The figures are based on quality materials.
Hip and valley rafter sizing.
This chart is for initial rough sizing hip and valley rafters work should be checked by an engineer before plans are finalized.
