Flat Roof Framing Spans

An essential part of planning a patio roof or gazebo project is determining the number size and spacing of rafters beams and posts according to the loads they will carry.

Flat roof framing spans. 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. Span calculator for wood joists and rafters also available for the android os. 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. 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.

Maximum rafter spans for a patio roof in areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot. Span exceeds 26 feet in length. 2 are indicated below. 1 ft 0 3048 m.

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. Roof load width rlw and floor load width flw can be determined from as1684 or from the images below. 25 psf max live load 20 psf t r602 7 1 allowable spans for df 2 headers for exterior bearing walls max. 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. Dead load weight of structure and fixed loads 15 lbs ft 2. Attached flat roof 1ao page14. Also available for the android os.

Spacing should be interpreted as the centre to centre distance between adjacent parallel members. Check sources for ava ilability of lumber in lengths greater than 20 feet. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. Allowable spans for df 2 headers for exterior bearing walls max.

Required size for a given span. 1 psf lb f ft 2 47 88 n m 2. Spacing inches dl 15 psf dl 25 psf ll 20 psf ll 20 psf 4 x 4.