![]() TABLE R802.4. Table R502.3.1(1) shall be used to determine the maximum allowable span of floor joists that support sleeping areas and attics that are accessed by means of a fixed stairway in accordance with Section R311.7 provided that the design live load does not exceed 30 pounds per square foot (1. Height of roof ridge measured vertically above the top of the rafter support walls. Height of ceiling joists or rafter ties measured vertically above the top of the rafter support walls. Where ceiling joists or rafter ties are located higher in the attic space, the rafter spans shall be multiplied by the following factors: The tabulated rafter spans assume that ceiling joists are located at the bottom of the attic space or that some other method of resisting the outward push of the rafters on the bearing walls, such as rafter ties, is provided at that location. The span tables are based on the International Building Code and International Residential Code and are available for visually graded and mechanically graded lumber. (continued) TABLE R802.4.1(1)-continued RAFTER SPANS FOR COMMON LUMBER SPECIES (Roof live load = 20 psf, ceiling not attached to rafters, L/Δ = 180) RAFTER 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. Find out how to calculate joist and rafter spans in one- and two-family dwellings using the span tables developed by the American Wood Council. Racking Span Tables - Use this tables to detect lengths, page, and spacing of rafters based on several factors such as species, load, grade, and spacing. Bedroom areas are sized for 30 lb live load plus 10 lb of dead load (20 lb for ceiling). These six tables cover the most common situations for 16 o.c. ![]() TABLE R802.4.1(1) RAFTER SPANS FOR COMMON LUMBER SPECIES (Roof live load = 20 psf, ceiling not attached to rafters, L/Δ = 180) RAFTER SPACING (inches) 2 pine or other material can span as a floor joist according to 2018 International Residential Code for living, bedroom, and storage areas. ![]() These span tables are the equivalent of other industry-standard span tables and are calculated to the same standards. These spans were calculated using our rafter calculation engine. In making your choice, consider how you will insulate your insulate your roof. Another option are 2 X 8 rafters spaced 24 inches o.c. 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. This span table is to the format and methodology given in BS 5268-7.5. Looking through the center of the table, we can find a couple of options. Part III Building Planning and Construction. Click on a span to generate a full calculation (you can adjust the exact span and slope). as a consideration for selection of joists and rafters. Loading conditions, refer to the AWC STJR. International Residential Code 2021 (IRC 2021) Code Compare. For other grades and species and for other Measured along the horizontal projection of the TABLE R802.5.1 (1) RAFTER SPANS FOR COMMON LUMBER SPECIES (Roof live load 20 psf, ceiling not attached to rafters, L/ 180) RAFTER. Based on the rafter spans in Tables R802.4.1(1) The braces shall be spaced not more than 4 feet (1219 mm) on center and the unbraced length of braces shall not exceed 8 feet (2438 mm).
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