![]() FIGURE R802.5.1 BRACED RAFTER CONSTRUCTION TABLE R802.5. It is also commonly expressed as a ratio of rise to run, or a fraction of the rise over the run. H R = Height of roof ridge measured vertically above the top of the rafter support walls. Span is typically measured horizontally along the rafter projection from the ridge to the outer edge of the supporting outside wall plate. H C = Height of ceiling joists or rafter ties measured vertically above the top of the rafter support walls. Ap 2019 Introduction These Boxspan® Residential Span Tables provide detailed product, design and typical installation information. Spans for rafters shall be in accordance with Tables R802.5.1(1) through R802.5.1(8). Note: Where ceiling joist s run perpendicular to the rafter, rafter ties shall be installed in accordance with Section R802.3.1. Freestanding Carports & Roofs Rafters Table 22 28 Purlins Table 23 29 Roof Beams Table 24 30 Common Connections 31 Material Specifications 35. South Holland Residential Code 2012 > 8 Roof-Ceiling Construction > R802 Wood Roof Framing > R802.5 Allowable Rafter Spans. (Uninhabitable attics with limited storage, live load = 20 psf, L/Δ = 240) CEILING JOIST SPACING (inches)įor SI: 1 inch = 25.4 mm, 1 foot = 305 mm, 1 degree = 0.018 rad. (Uninhabitable attics without storage, live load= 10 psf, L/Δ = 240) CEILING JOIST SPACING (inches)Ĭheck sources for availability of lumber in lengths greater than 20 feet.įor SI: 1 inch= 25.4 mm, 1 foot= 304.8 mm, 1 pound per square foot= 0.0479 kPa.Ī. To calculate the maximum spans of species not shown above, use the Span Calculator or the Span Tables for Joists and Rafters on the American Wood Council website.Shall be in accordance with Tables R802.4(1) and R802.4(2).įor other grades and species and for other loading conditions,ĬEILING JOIST SPANS FOR COMMON LUMBER SPECIES To calculate maximum rafter spans using different design criteria (load, snow load, spacing, grade, etc.) for these common lumber species, see the International Residential Code (IRC). ![]() Download PDFs, see examples and refer to SFPA’s publication for more details. Another option are 2 X 8 rafters spaced 24 inches o.c. Find the maximum spans for live and dead load, wet-service and dry-service floor joists and rafters based on design values for visually graded Southern Pine dimension lumber. The span values (displayed above) are from the American Softwood Lumber standard sizes. The table states that 2 X 6 rafters spaced 16 inches on center (o.c) can span a maximum distance of 13 feet 5 inches. Rafters with ceiling not attached to rafters, ground snow load = 50 Psf, dead load = 20 Psf, deflection limit L/180 The following span table uses a moderate snow load of 50 Psf, but yours could be more or less. Loads are calculated in accordance with Table 3. Loads are calculated in accordance with Table 3.1 of AS/NZS 1170.1:2002. Uniform load tables for APA-trademarked structural panels manufactured/qualified in accordance with APA PRP-108. Consult your local building code authority to determine the snow load in your area. This is set by the roof use you selected in the previous screen and cannot be modified. Span tables and design values for joists and rafters in one- and two-family dwellings. ![]() ![]() Note: Snow load factors can be specific to the regional location of a structure. Rafter Span Tables Rafters with ceiling not attached to rafters, live load = 20 Psf, dead load = 20 Psf, deflection limit L/180 The braces need to be supported by a bearing wall, shown in the diagram above.Įxample: In the rafter span table below, the highlighted cell (13-0) indicates that a 2" x 8" Douglas Fir rafter, with a grade of #2, spaced 24" apart, can have a maximum span of 13 feet - 0 inches (13-0) if designed for a live load of 20 Psf, and dead load of 20 Psf. The spanning capacity of load-bearing members is determined by a combination of stress grades and timber sizes and product engineering. Note also that you can break up the span of a rafter by adding a purlin and bracing to the underside. Knowing the right spans is crucial for building safely and making sure floors and roofs stay strong and dont sag or collapse. When calculating the maximum span of a rafter, use the horizontal distance between two vertical supports.
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