Hardwood lumber grades and grading rules have been established and are governed by the National Hardwood Lumber Association or NHLA. Flooring grades have been set and are maintained by the National Oak Flooring Manufacturers Association or NOFMA.

Sawmills and their customers use the NHLA grading system, which describes the amount of usable clear material in a board. Boards with the highest grade—FAS—are long, wide and free of character marks. Select boards may contain slight character marks such as pinholes or small tight knots. The NHLA grading system includes:

NHLA Grading System
• FAS No. 1 Common
• Select No. 2 Common
  No. 3 Common

The NOFMA standards grade oak and other species of flooring. This system is appearance-based with grades determined by the occurrence of character marks. These grades include:

NOFMA Grading System
• Clear No. 1 Common
• Select No. 2 Common

Clear and Select grades are further identified by the sawing method. NOFMA also has separate grading standards for pre-finished flooring–Prime, Standard and Tavern.
Hardwood logs become lumber by one of several sawing methods. Each gives hardwood boards a distinct grain pattern, along with performance characteristics you need to consider when specifying.

Plain-Sawn Lumber: cutting tangentially to a tree’s growth rings produces these boards. That creates the familiar “flame-shaped” or “cathedral” grain found in most hardwood flooring and millwork. This sawing method also produces the most lumber from each log, making it a cost-effective design choice.

Quarter-Sawn Lumber: This method means cutting a log radially, or 90-degree angle to the growth rings. This produces vertical graining, and results in fewer and narrower boards per log, which increases costs. Quarter-sawn boards are popular for decorative applications such as cabinet faces and wainscoting.

Rift-Sawn Lumber: Rift sawing at a 30-degree or greater angle to the growth rings produces narrow boards with accentuated vertical or straight grain patterns. These boards are often favored for fine furniture and other applications where matching grain is important. Rift-sawn lumber is available in limited quantities and species.
©2008 Industrial Plywood, Inc.