![]() ![]() Neither SFPA, nor its members, have knowledge of the quality of materials, workmanship or construction methods used on any construction project and, accordingly, do not warrant the technical data, design, or performance of the lumber in completed structures. Both the hip and valley rafters form a 45 degree angle. The conditions under which lumber is used in construction may vary widely, as does the quality of workmanship. The valley rafter is the structural board which forms the valley at an inside corner of the roof. The design values contained herein are based on the Southern Pine Inspection Bureau’s Standard Grading Rules for Southern Pine Lumber (2002 edition with supplements) and modified as required by AWC’s National Design Specification® (NDS®) for Wood Construction (2012 edition).Īccordingly, SFPA does not warrant that the design values on which the span tables for Southern Pine lumber contained herein are based are correct, and specifically disclaims any liability for injury or damage resulting from the use of such span tables. SFPA does not grade or test lumber, and accordingly, does not assign design values to Southern Pine lumber. The maximum spans provided herein were determined on the same basis as those in the code-recognized Span Tables for Joists and Rafters(2012 edition) and Wood Structural Design Data (1986 with 1992 revisions), both published by the American Wood Council (AWC). The primary purpose of this publication is to provide a convenient reference for joist and rafter spans for specific grades of Southern Pine lumber. Limit State Capacities - Recommended maximum single spans (m) Table 1: ROOF BEAMS, JOISTS, RAFTERS, PURLINS Roof weight 40 kg/m2 EXCLUDING PLASTER BOARD CEILINGS IN RESIDENTIAL - see Table 2 CODE BEAM SIZE (mm) SPACING (mm) 2400 T257aP10 248 x 71 8.45 7.84 7.06 6.54 5.85 5. Forest Products Machinery & Equipment EXPO.Headers & Beams : Allowable Load Tables The spacing of roof rafters is just one of the components used to determine the minimum size of the roof rafter.Headers & Beams : Size Selection Tables.Collar ties, contrary to popular belief, do not prevent walls from spreading.Where they are required, they should be installed on every other rafter where rafters are on 24-inch centers.Collar ties are probably not needed if approved metal connectors were used to fasten the rafters to the ridge.InterNACHI inspectors should not call out a lack of collar ties as a defect unless they know that collar ties were required in the jurisdiction where the home is located at the time the home was built. They may or may not be required, depending on the jurisdiction.In high-wind areas, uplift can tear a roof off of a house if it's not properly attached.Ĭollar ties and ridge straps should be installed on roof with a minimum slope of 3:12, a maximum wind speed of 100 miles per hour, and a maximum roof span of 36 feet. They must be spaced no more than 4 feet (1219 mm) apart. They must be at least 1 inch by 4 inches (25 mm by 102 mm). If collar ties or ridge straps are installed to connect opposing rafters, they must be located in the upper third of the attic space. Ridge straps are permitted to replace collar ties. A collar tie is a tension tie in the upper third of opposing gable rafters that is intended to resist rafter separation from the ridge beam during periods of unbalanced loads, such as that caused by wind uplift, or unbalanced roof loads from snow.
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