3/24/2024 0 Comments Southern pine span tables rafters![]() ![]() Q: Did design values for other Southern Pine lumber products change?Ī: No. Compression perpendicular-to-grain (F cortho).Q: Which lumber properties have the same design values? Q: Which lumber properties have new design values? Proposed design values are submitted to the Board of Review of the ALSC, and approved following a careful review and recommendation from the U.S. ![]() All testing and data analysis must be completed in accordance with approved standards. SPIB is responsible for developing and publishing design values for Southern Pine. Design values for the minor strength properties of shear and compression perpendicular-to-grain are based on published clear-wood properties.ĭesign values for structural lumber undergo a rigorous approval process. Design values for stiffness, as well as the major strength properties of bending, tension, and compression parallel-to-grain, are based on data from destructive testing of samples of commercially-produced structural lumber. SPIB did not specifically study why a change occurred this time, but a change in the timber resource mix is one of many variables that can affect the strength of structural lumber.Ī: Design values provide guidance for designers to calculate the performance of a structural system and are assigned to six basic lumber properties. The last major change occurred in 1991 when design values for Southern Pine and other North American species were first published based on In-Grade testing of full-size samples of commercially produced lumber. The first significant lumber tests began in the 1920s, resulting in design values based on the strength of small clear-wood specimens. Comprehensive lumber testing is conducted as new technology becomes available or as warranted by changing resource data. The lumber industry conducts ongoing testing and invests millions of dollars to provide the most accurate and reliable design values for structural lumber. The integrity of existing structures designed and built using design values meeting applicable building codes at the time of permitting does not change.Ī: Design values have changed multiple times over the years based on available test data. Like other building materials, wood products used in construction must meet building code requirements enforced at the time. New design values only apply to new construction, not existing construction. Q: Do new design values affect existing structures?Ī: No. The following frequently asked questions and answers were developed to assist designers with implementation of new southern pine design values. ![]() More than 7,400 full-size samples of commercially-produced Southern Pine were destructively tested in a two-step process, resulting in more than 300,000 data points. SPIB and Timber Products Inspection worked cooperatively to complete a full In-Grade testing matrix as required by consensus standard ASTM D1990, Standard Practice for Establishing Allowable Properties for Visually-Graded Dimension Lumber from In-Grade Tests of Full-Size Specimens. As a rules-writing agency, SPIB must follow a rigorous approval process to establish design values for Southern Pine lumber. The American Lumber Standard Committee (ALSC) Board of Review approved changes to design values for all grades and all sizes of visually-graded Southern Pine and Mixed Southern Pine lumber, with a recommended effective date of Jto allow for their orderly implementation.Īccordingly, new design values for all sizes and grades of visually-graded Southern Pine dimension lumber were published in the Southern Pine Inspection Bureau’s (SPIB) Supplement No.13 to the 2002 Standard Grading Rules for Southern Pine Lumber. ![]()
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