Urban Wood - Wood Grading

A Woodworker's Resource

Grading "rules" and terms for Urbanwoods

Buying Hardwoods, the RULES
(Source: American Furniture Design Co.)

Most lumber in the country is sold under a grading system developed by the National Hardwood Lumber Association (NHLA). The primary focus of the grading system is to establish the area of clear face cutting in each board.

The best grade is FAS (First and Seconds) which yields the largest percent of clear wood. F1F (FAS-one face) and selects are graded for each side of the board, with one side FAS quality and the other No.1 Common. Lower grades are No.2A & No.2B Common, which yield half clear wood; No.3A Common which yields one-third clear wood; and No.3B Common, which yields one-quarter clear wood.

The NHLA also set the rules for measurement and tally. Most lumber is sold by the board foot, which is system of volume measurement based on a piece of wood that is 1' wide, 1' long and 1" thick. However, some specialty items and milled stock are sold per linear foot, a system that doesn't figure in the width and thickness. Hardwood thicknesses are expressed in quarters rather than inches. For example 1" thick lumber is called 4/4, 1 1/2" is called 6/4 and 2" thick stock is 8/4.

All the rules go out the window when picking figured hardwood. The market for figured or decorative woods has expanded in recent years as larger retail yards have added to their inventories and smaller, or specialty yards have emerged. The biggest problem with buying figured hardwoods is the lack of uniform grading rules. There are no NHLA grading rules for figured woods. Figure is the driving factor in establishing the price and grade is secondary. Some of the more popular species of figured woods are cherry, curly maple, walnut, birch and mahogany. These woods are generally available in thicknesses of 4/4 to 16/4. Widths of 20"-24", or wider, are not uncommon in 4/4 and 5/4.

Summary of NHLA Rules

The rules for determining grade correspond to the percentage of usable lumber in a given board.

There are seven main grades in hardwood lumber. Although some species have specific rules generally the following grades apply. These grades are based on rough lumber and the grade is determined from the poor face of the board.

FAS (Firsts and Seconds)

This is the highest grade and will yield 83.3% Clear lumber on the poor face. The FAS grade will provide the hardwood lumber user a board containing long, wide, clear cuttings. This grade is most often used by, molding manufacturers, in architectural millwork, and custom cabinet shops. The FAS grade lumber will include lumber that will yield from 83-1/3% to 100% clear wood in minimum sized cuttings at least 3" wide by 7’ long or 4" wide by 5’ long. The width and the length of the board determine how many cuts may be used to obtain the percentage of clear cut lumber. The longer and wider the board the greater the number of cuts that may be used to obtain the percentage of clear cut lumber. The minimum size kiln dried board in the FAS grade is 5-1/2" wide by 8’ long. Note: a common misconception is that a FAS board must be 6" or wider, however this width requirement applies to green lumber, the requirement for kiln-dried lumber is the 5-1/2" width which allows for the shrinkage that occurs during kiln drying.

The following diagram shows examples of two boards with the cuts needed to make a FAS grade. The clear unshaded areas are the examples of clear cuts. The shaded areas contain the defects and are not used in the clear cuttings, although there may well be good useable material in the shaded areas it does not meet the minimum size cut for the FAS grade.

1F (1 Face)

The 1F grade is almost always grouped together with the FAS grade. The 1F grade is obtained by grading both faces of the board. The best face must meet the requirements of an FAS grade, while the poorer face must meet the grade requirements of an #1 Common grade.


This is the second highest grade it also is determined somewhat differently in that the grade is determined by the better face of the board. The select grade is essentially the same grade lumber as the 1F grade, except for the minimum board size.A select board will have a better face that makes FAS while the back will be #1 common.

#1 common

This is still considered an upper grade suitable for general woodworking. This board will yield 66.6% usable lumber on the poor face.

#2 and #3 Common

The four bottom grades are #2a common, #2b common, #3a Common, and #3b common. These are primarily used for specific manufacturing such as pallets and hardwood flooring. The #1 Common grade will provide the hardwood lumber user with medium sized clear cutting. This grade is, most often used by cabinet manufacturers, cabinet door manufacturers, and furniture manufacturers. The #1 Common grade will include boards that will yield 66-2/3% to 83-1/3% in minimum size clear wood cuttings of at least 3" wide by 3’ long or 4" wide by 2’ long. The greater the width and length of the board the greater the number of clear wood cutting allowed to achieve the yield percentage. The minimum size board allowed in the #1 Common grade is after kiln-drying 2-1/2" wide by 4’ long. Note: the minimum size for green lumber is 3" wide by 4’ long.

The following diagrams show examples of two #1 Common boards. The clear unshaded areas are examples of how the board would be cut to make the #1 Common grade. The shaded areas are examples of areas that contain defects that cannot be used in clear cuts. The shaded areas may well contain good clear useable material, however it does not meet the minimum size requirement of cut size for a #1 Common grade.