Flat Roof Framing 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.

Flat roof framing spans. 25 psf max live load 20 psf t r602 7 1 allowable spans for df 2 headers for exterior bearing walls max. R cb150 16 beam span table used w 3600 width of frame rafter span χ 6410 fascia beam span the cb150 16 beam achieves the 6000mm span for the fascia beam and can be used for the rafters. 1 ft 0 3048 m. Ceiling joist span use this table to determine the maximum lengths of ceiling joists based on species of lumber joist spacing and joist size.

Span calculator for wood joists and rafters also available for the android os. Allowable spans for df 2 headers for exterior bearing walls max. Spacing inches dl 15 psf dl 25 psf ll 20 psf ll 20 psf 4 x 4. 2 are indicated below.

Also available for the android os. Dead load weight of structure and fixed loads 15 lbs ft 2. Spacing should be interpreted as the centre to centre distance between adjacent parallel members. Roof load width rlw and floor load width flw can be determined from as1684 or from the images below.

Live load is weight of furniture wind snow and more. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. Consult local building codes for snow load capacity and reference the span tables for joists and rafters published by the american wood council awc as a general rule roofs that have a high human occupancy rate should be framed with rafters every 16 structures such as sheds or barns can be frames with rafters every 24. Check sources for ava ilability of lumber in lengths greater than 20 feet.

Allowable spans for open beam ceilings 1 2 7 lumber grade lightweight roofing tile roofing douglas fir larch no 2 or better nominal size inches o c. 1 psf lb f ft 2 47 88 n m 2. Required size for a given span. Rafter spans can be extended slightly beyond what the rafter tables suggest when there is a cantelever extending beyond the supporting wall.

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. Span exceeds 26 feet in length. 25 psf max live load 40 psf roof limited storage attic t r602 7 1 size 20 ft building width nj 28 ft building width nj.