Rules Corner: Rules, Guidelines, and the Role of AI in Modern Lumber Grading

Many times over my career, I have heard that the NHLA Rules were more of a guideline than actual rules. The fact that they are published and have well-defined and written descriptions of the minimum acceptable boards in each grade—and have been used as the hardwood industry standard for over 125 years—make them rules.

To clarify the distinction: guidelines offer flexibility and recommend-ed best practices, while rules are mandatory standards that must be followed and include defined consequences for non-compliance. The NHLA Rules fall firmly into the latter category.

As most people know, humans make mistakes, and this includes lumber inspectors. Mistakes are reasonable, especially with higher rates of production involving a variety of species and defects. This is why they’re limited in the Sales Code to 80% on grade and 4% of the money value. Some mistakes are due to under-training and other fac-tors. The minimum standard for grades outlined in the NHLA Rules Book is still their primary objective in most cases. With the invention of image-based AI grading systems currently used in many hardwood operations, several areas of concern arise.

With AI-based grading systems, grading outcomes are determined by how the system is programmed. If parameters are intentionally set to recognize less clear wood than the NHLA Rules require, the resulting grades would not meet NHLA standards. This would not apply to proprietary grades, provided that the grade names used in representing the lumber were not defined in the NHLA Rules Book. This practice represents a deliberate departure from the minimum standards defined in the NHLA Rules.

Any company grading lumber for shipment or receipt—whether using a certified inspector or an AI-based system—should ensure grades align with the minimum standards outlined in the NHLA Rules. Periodic audits by a National Inspector can help verify accuracy and maintain confidence in the grades being shipped or received.

By DANA SPESSERT, Chief Inspector