Below is a letter from the American Wood Council:
Recent changes to design values for southern pine dimension lumber resulted in the spans set forth in the 2012 Virginia Residential Code (VRC) Girder and Header Span tables to be applicable only to #1 grade southern pine. Footnote “b” in tables 502.3.3(1) and (2), tables 502.5 (1) and (2) states:
“Spans are based on minimum design properties for No. 2 Grade lumber of Douglas fir-larch, hem-fir and spruce-pine-fir. No. 1 or better grade lumber shall be used for southern pine”.
The change to Footnote “b” was intended to be a temporary fix to the span tables since final design values for southern pine were not approved until June 2013; however, this change has proven to be problematic in Virginia, since lumber suppliers do not typically carry #1 grade southern pine.
The American Wood Council would like to offer two suggestions that designers/builders may use as an alternative and which Building Code Officials may rely on as acceptable.
- The 2012 Virginia Residential Code, Section 301.1.1 lists the 2012 Wood Frame Construction Manual (WFCM) as an alternative design option. A 2013 Addendum to this document provides a method of using the 2012 WFCM span tables with #2 grade southern pine that would also apply to the VRC girder and header span tables. To use #2 grade southern pine with the VRC girder and header span tables, multiply the tabulated spans by 0.93.
- Header and girder span tables in the 2015 Wood Frame Construction Manual are based on current minimum design values for # 2 grade lumber of Douglas fir-larch, hem-fir, southern pine, and spruce-pine-fir. It is referenced in the 2015 IRC (although not the 2012) and could therefore be considered as an acceptable alternate method.