The NHLA (National Hardwood Lumber Association) grading system is the standard grading system used for North American hardwood lumber. The system is based on a set of rules that define various grades of hardwood lumber based on the number and size of defects present in the wood.
The NHLA grading system is used to determine the value of hardwood lumber in the marketplace. The grades are based on the amount of clear, defect-free wood that is present in a given board, and the appearance of the wood.
There are several different grades in the NHLA system, each with its own set of rules and requirements. The most common grades include:
- FAS (Firsts and Seconds) - the highest grade, consisting of boards that are at least 6 inches wide and 8 feet long, with minimal defects.
- Select - slightly lower quality than FAS, but still very high quality, with minimal defects.
- No. 1 Common - contains more defects than FAS or Select, but still suitable for many uses.
- No. 2 Common - contains more and larger defects than No. 1 Common, but is still usable for some applications.
- No. 3 Common - the lowest grade, with the most defects and used mainly for industrial purposes.
The NHLA grading system is used primarily in the United States and Canada, and is recognized internationally as a standard for hardwood lumber grading.