Rafter spans for southern yellow pine douglas fir and eastern spruce.
Rafter span roof span tables.
Loads are calculated in accordance with table 3 1 of as nzs 1170 1 2002.
For lesser grades spans should be shorter.
2 are indicated below.
For pitched roofs flat roofs and ceiling joists.
The spans in this table are based on a maximum supported rafter span of 16 feet where the supported span is the total horizontal distance spanned by the roof rafters divided in half not the diagonal distance or the length of the rafter.
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.
The calculated spans assume fully supported members properly sheathed and nailed on the top edge of the joist or rafter.
Dead load weight of structure and fixed loads 15 lbs ft 2.
Use this table to determine the maximum lengths of ceiling joists based on species of lumber joist spacing and joist size.
Rafter spans can be extended slightly beyond what the rafter tables suggest when there is a cantelever extending beyond the supporting wall.
These span tables assume installation of at least three joists or rafters that are spaced not more than 24 on center.
Live load is weight of furniture wind snow and more.
1 ft 0 3048 m.
Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no.
The imposed uniformly distributed live load in the main span.
Surveyors span tables for designing roof rafters.
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.
This is set by the roof use you selected in the previous screen and cannot be modified.
1 psf lb f ft 2 47 88 n m 2.
So this table could accommodate a house with a total rafter span or house width of 32 feet.
The tables below give maximum spans for rafters and beams.
Tables 2l and 2h list the sizes and spans for pergola or carport beams in low wind speed and higher wind speed areas.
Click here for structural design calculations.
1 1 based on the horizontal projection of the roof rafter span.
Span calculator for wood joists and rafters also available for the android os.
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.
Keep in mind that these are maximums in other words shortening spans slightly will result in a more solid structure.
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.
