Hardwood flooring is sorted and sold in different grades based on its color uniformity, average board lengths, size of knots, color streaks and any imperfections on its face. North American domestic species, such as Oak, Maple, Hickory or Pine, use different grading terminology and standards. These are the most common quality grades:
Red Oak & White Oak
Clear: Minimal color and character variation, uniform grain, very little sap, average length of 3-1/2’ in each bundle, highest quality.
No. 1 Common: Distinct variation in color and grain, noticeable color streaks, some knot imperfections, average length of 2-1/2’ in each bundle, third best quality.
Select: Shows some variation in tones and grain, minimal knots and color streaks, average length of 3’ in each bundle. Second highest quality.
No. 2 Common: Strong variation in color and character, noticeable color streaks, significant knots, boards ranging from light to dark, average length of 2’ in each bundle, fourth best quality.
Character/Utility Grade: Lowest grade. Expect distinct light and dark boards, large knots, streaks and pinholes. Boards are very short in lengths (1’ to 2’) and may have splits, racks and other defects.
Maple & Birch
First Grade: This grade is the highest for these species and is almost entirely free of defects. Some minor variations in the natural color of wood, minimal knots, occasional dark green or black spots or streaks and small burls.
Second Grade: Expect more wood disparity and some imperfections which can include color variation, streaks, stained sapwood, sound tight knots and slight checks. The following are also permitted: small rough spots, slightly torn edges, and small bark streaks.
Third Grade: All defects are tolerated in this grade, but it cannot have knot holes larger than ¾”, heart checks and other imperfections that would compromise floor quality. This grade is rustic in appearance.
Hickory First Grade: This is the highest grade for hickory. It is nearly free of character marks and defects and has a uniform appearance. Color is not a defect and this grade may contain a mix of sapwood and heartwood. The following are admitted: small knots no more than 1/4" in diameter; dark streaks that do not exceed 3", slight checks, and small burls.
Hickory Second Grade: This grade shows minor imperfections and colors. These include knots, checks, streaks, stains, splits, and broken knots of up to 1/2" in diameter. Predominantly dark, discolored pieces are not allowed.
Hickory Natural: This grade features distinct but natural variations in color and grain. Small knots, mineral streaks, and staining are allowed. The boards in this grade are slightly longer than those found in Third Grade flooring.
Hickory Third Grade: This grade is ideal for applications where a rustic look is desired. Although the wood is firm, it contains many types of defects that will readily fill, including knot holes, bird pecks and worm holes.