The Main Types of Hardwood Flooring Grades, Explained

The Main Types of Hardwood Flooring Grades, Explained

The lumber manufacturing industry has come a long way in the last decades. As industrial and technological innovation continues, the lumber manufacturing process has evolved and become much more complex, which has led to the creation of lumber ‘grades.’ Producers ‘grade’ their lumber for quality assurance purposes, to ensure consumers that the hardwood or engineered wood planks they’re acquiring are the right quality for their needs. 

Hardwood flooring grades group types of flooring that boast similar qualities to ensure consistency across products manufactured at different mills across the country. These grades inform the consumer about what they can expect from a product, whether it’s surface characteristics, lengths, milling and sawing tolerances, or durability. Grading lumber also helps manufacturers price their products correctly, according to quality. 

Who establishes the hardwood flooring grades in the US?

Hardwood flooring grades are established by industry associations, like the National Hardwood Lumber Association (NHLA), the National Oak Flooring Association, or the Maple Flooring Manufacturers Association. The guidelines established by these associations apply to over 90% of the solid wood manufactured in the U.S. and Canada. 

Additionally, these associations are the go-to mediator that settles grading dispute cases; however, manufacturers must belong to the association to be able to benefit from grading inspection services. In some cases, hardwood flooring manufacturers establish their own proprietary grades, for sales or marketing purposes. 

At First Atlanta Flooring, we follow the grading guidelines established by the National Wood Flooring Association. Their grades are widely accepted, so much so that even non-member mills follow their guidelines to classify their lumber. The NWFA guidelines cover unfinished species like red or white oak, maple, ash, beech, birch, and hickory/pecan, as well as prefinished oak flooring. For softwoods, grades are established by the Southern Pine Inspection Bureau, the West Coast Lumber Inspection Bureau, or the Western Wood Products Association. 

How is hardwood flooring graded?

While a trained eye can determine the grade of hardwood flooring simply based on appearance, the grading process is complex, and takes into account various factors, including length, thickness, and milling tolerance. 

Oak is the most popular hardwood in the U.S., and it boasts four basic grades: Clear, Select, Common #1, and Common #2. Clear oak is the most uniform in appearance, free of knots, marks, or color variances, and consists mainly of heartwood. Select oak is also uniform in appearance, but it features more of the natural characteristics of the hardwood, like knots and color variations. 

Common #1 and #2 are popular due to the natural look and features of the hardwood, and because they have ‘more personality.’ The Common grades bring more character and make each hardwood plank unique, and feature knots, marks, color variations, burls, checks, crooks, flecks, and more. 

These hardwood grades can also be combined into different combinations, such as Select & Better, or #1 Common & Better Shorts, depending on the length or quality of the planks. 

What are the different grades of hardwood flooring?

The three main hardwood flooring grades are Select, #1 Common and #2 Common. These grading guidelines primarily apply to oak wood, because it is the most popular species in the U.S., but they are also used to grade other types of hardwood. 

1. Clear

Clear oak hardwood consists mostly of heartwood, and presents with minimal color variations or character marks, and a uniform, consistent look. This grade does present the natural heartwood color variations or grain patterns. 

Industry guidelines for the clear oak grade accept the following specifications, or features: ⅜’’ bright sapwood, entire length of strip; one thin brown streak, 3’’ long allowed every 6’; small burls; fine pin wormholes; small tight checks. Clear oak planks are usually packaged in 11/4’ or longer bundles, with an average length of 33/4’, bundled or nested. 

2. Select 

The Select hardwood grade allows all natural variations in color that result from the contrast between heartwood and sapwood. Select hardwood also presents with minimal character marks, like small knots, mineral streaks, wormholes, and slightly open characters. The combination between heartwood and sapwood also results in slight color interruptions, which are accepted. 

Character markes accepted for the Select grade include: slight imperfections in the milling process; a small, tight know every 3’; pin wormholes; burls; slightly open check; slight imperfections in face work; a slight quantity of bark on the sides or back of the planks; and intermittent brown streaks not exceeding ¼’’ width. 

Select oak planks are usually bundled to be 11/4’ or longer, with an average length of 31/4’ bundled or nested. 

3. #1 Common

The hardwood grade known as #1 Common is characterized by visible color variations and multiple character marks, including wormholes, knots, open checks, and even splits and dark machine burns across the face of the wood. However, checks and knot holes should be sound and readily filled, and broken knots need to be under ½’’ in diameter. 

With #1 Common hardwood, obvious color variations and varying character marks are to be expected, and it’s a popular hardwood grade due to its natural feel. However, only minor imperfections are accepted, and the planks must still meet certain thickness or machining requirements. Occasional dark machine burns should not exceed ½’’ width or 1/64’’ depth. 

#1 Common hardwood is packaged in 11/4’ bundles or longer, with an average length of 23/4’ bundled or nested. 

4. #2 Common

The #2 Common hardwood grade can present with visible manufacturing variations and character marks, including knot holes, open, large wormholes, color differences, machine irregularities, and more. This type of hardwood is a popular option for high-traffic areas, such as living rooms, dining rooms, or offices, because the imperfections and characters in the wood serve to hide any damage from heavy use, like scratches, spills, or dents. 

When it comes to #1 Common hardwood grading, there are some marks and flaws in the planks that are not acceptable, such as large broken knots, advanced rot, shattered ends or sides, excessive damage from millwork, and other grave defects. Dark machine burns that are over 3/64’’ deep are also not accepted. 

#2 Common hardwood planks are usually packaged in bundles that are 11/4’ and longer, with an average length of 21/4’ bundled or nested. 

There are, of course, other lumber grades established by the NWFA guidelines, including 1 ¼’’ Shorts Oak, and different grades for prefinished oak, like Prime, Standard, and Tavern Prefinished Oak. There are also several different grades to distinguish different types of maple, birch, beech, hickory/pecan, and ash, but Oak is by far the most common option in the U.S. Hardwood flooring grades can also be combined; for instance, pieces graded #1 Common, Select, or Clear, are often bundled together as #1 Common & Better. 

The First Atlanta Flooring shop features #1 Common & Better products in varying lengths, colors, thickness, both prefinished or unfinished. We carry only NWFA-certified hardwood floors, made in the U.S.