TFG Events & Workshops

Tom Nehil

Co-Founder

Nehil-Sivak

Timber Grading: Why? How? Then What?
Dick Schmidt and Tom Nehil present a full day of sessions relating to the why, how, and what of timber grading.

In this session, the first of three addressing grading of lumber and timber, we will look at the "how come" of stress grading. We will look at the requirements of the building code and how they are expressed in the grading rules - how those rules came about in the first place and how they are applied now. We will relate the grading rules to the mechanical properties of real-life timbers, distinguishing stress grading from appearance grading.

In part two of a three-part series of presentations, we will review the rules established by the American Lumber Standards Committee for determining the stress grade for timber. Emphasis will be on techniques for measuring knot size and slope of grain. Timber samples with various strength-reducing characteristics will be available so that attendees can gain hands-on experience with the methods discussed.

In part three of a three-part series of presentations, we will discuss how stress grading results may be used to determine design values (allowable stresses) for lumber and timber. Applications include in situ evaluation of a structure as well as grading of reclaimed material. The use of ASTM D245 to generate design values using the strength-ratio approach will be reviewed, reducing the need to rely on the NDS for material not included in the recognized species combinations and for sticks with smaller defects than those defined as the limits for a particular grade. Physical testing will be included to demonstrate the impacts of knots and slope of grain on member strength.