E. The varying relationships between the logs, the rules, and the lumber itself are complex and not directly proportional to anything measurable. Consequently, the board foot units defy accurate conversion to any other English or metric unit of measure used in national or international commerce for wood products. F. Board foot units and rules do not reliably estimate other wood products. Not all products manufactured from trees and logs are lumber. Posts, poles, chips, veneer, and various other products cannot be accurately estimated in terms of board feet.
More timber is chipped, peeled, sliced, or otherwise processed now than in the past.
Even mills that manufacture lumber as their primary product usually produce products other than lumber. The board foot rules treat all the portions of the logs not suitable for lumber as zero volume. However, this material must be handled as other products or waste and some estimate of this volume in units other than board feet is necessary. G. Board foot volume is not closely related to weight, which is important in estimating costs of log hauling. It is a poor unit for estimating logging costs.