SBCA's Lumber Design Value Implementation Guidance
Originally published by: SBCA — July 23, 2012
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As a reminder to all structural component manufacturers, SBCA has provided an engineered use guidance document for implementing the reduced Southern Pine lumber design values that went into effect on June 1, 2012 (click on the pdf link below to view this document, key text has been highlighted for emphasis). The document states:
1. How should builders, building officials, and building design and structural building component industries react with respect to the lumber design values used to provide structural resistance to loads?
a. Everyone should follow the lead of the lumber industry’s engineering association, the American Wood Council (AWC), as well as the ALSC ruling and SPIB Supplement No. 9 by using “6/1/12 on” (i.e. reduced June 1, 2012) design values for all structural resistance.
2. What about projects that have been designed using pre June 1, 2012 lumber design values that are on-going projects after June 1?
a. Everyone should follow AWC’s lead by having transitioned to using the “6/1/12 on” design values for all structural resistance so that one is in compliance with the ALSC Ruling and SPIB Supplement No. 9.
b. The CM may be asked to use the “pre 6/1/12” design values. As a condition of the use of these values, the CM should require written consent from the project Building Designer (e.g. Engineer of Record, or Building Owner) to the CM’s use of these “pre 6/1/12” values.
3. I thought I could just change over to the new design values when the design values are adopted by the local jurisdiction or the local building official says I have to. Is this true?
a. Unfortunately this concept is not in alignment with what the building code says.
b. The 2006 and after codes state the following; “Load-bearing dimension lumber for rafters, trusses and ceiling joists shall be identified by a grade mark of a lumber grading or inspection agency that has been approved by an accreditation body that complies with DOC PS 20 or in lieu of a grade mark, a certificate of inspection issued by a lumber grading or inspection agency meeting the requirements of this section shall be accepted.[IRC R802.1].”The load-bearing capacity will be defined by allowable lumber design properties as designated by the grade mark that complies with DOC PS 20 or in accordance with AFPA/NDS.
c. Both the grade marked design values posted by SPIB and AFPA on their website currently show that “6/1/12 on” design values are the current design values all engineered uses of lumber shall be using.
Further SFPA (http://www.southernpine.com/pdf/QA_newdesignvalues.pdf) provides the following information with respect to what the grade stamp means as it relates to the new design values:
