Timber in Historic Structures: Deriving Allowable Design Values
Tom Nehil will review how timber species identification and appropriate use of grading rules can enable us to responsibly assign allowable design values to lumber and timber in historic buildings. He will describe current work in the Timber Frame Engineering Council to provide training and establish standards for informed application of grading rules to timber in existing buildings by establishing a grasp of the underlying science behind the grading rules. This deeper understanding, built on 130 years of testing and standards development in stress grading of timber, can enable us to use, or in some cases even improve on, the allowable design values presented in the National Design Specification for Wood Construction (NDS©). When combined with structural analysis, differentiation between timber characteristics and mechanical alterations, and determination of critical sections, we have powerful tools to get the most from existing timber framing and avoid both unnecessary expense and possible compromise or loss of historic fabric. This facilitates conservation and appropriate use of our built cultural resources.
Tom Nehil is a structural engineer in Kalamazoo, Michigan, where he specializes in evaluation, preservation and adaptive reuse of historic buildings. Tom is a member of the Timber Frame Engineering Council that is part of the Timber Framers Guild, and chairs the Timber Grading Training Committee for the Council. He is also active with the Michigan Barn Preservation Network and the Michigan Historic Preservation Network among other professional organizations. He is a regular instructor at Tillers International in Kalamazoo where he teaches wood identification, timber frame design, and traditional stone masonry.
This event is generously sponsored by the Timber Frame Engineering Council and Nehil-Sivak Structural Engineers.