Among the many qualities that influence the appearance of any particular hardwood flooring is the grade of the wood. Almost all boards sold for hardwood flooring in the U.S. are graded according to standards originally laid out by the National Oak Flooring Manufacturers Association (NOFMA) to help create consistency in the quality of Oak flooring in the U.S. These standards are now used to grade virtually all hardwood flooring throughout the country and are promoted and upheld by the National Wood Flooring Association (NWFA).
While the NOFMA grading system relates closely to the guidelines set out for all hardwood lumber by the National Hardwood Lumber Association (NHLA), the NOFMA system gives more attention to the appearance or absence of certain characteristic marks than to other considerations weighed by the NHLA, which must grade wood for uses ranging from cabinetry to building frames. NOFMA grades, then, are largely an indicator of what the face of a board can be expected to look like, rather than an assessment of inherent quality, stability, hardness, or other factors.
Oak Flooring Grades
The grading options below are descriptions provided by the NWFA and represent Oak Flooring species only. This is meant to provide a quick overview of how grading controls the look of certain lumber while being milled and sorted. These grades are commonly used, but not offered in every type of lumber. For grading information on other species, be sure to contact one of our representatives.
Clear Grade Oak
A mostly heartwood flooring product that allows all the natural heartwood color variations with minimal character marks and limited color variation. This combination features the infinitely variable grain patterns with the minimal distraction from character marks and color variation.
Select Grade Oak
Generally a cleaner overall grade, this contains all the variations in coloration produced by the contrasting differences of heartwood and sapwood. Also included are minimal character marks, such as small knots, worm holes, and mineral streaks, as well as slightly open characters. The combination creates a floor where the light sapwood and dark heartwood are combined with small characters and other small color interruptions.
No. 1 Common Oak
A flooring product characterized by prominent color variation that also contains prominent characters (with size limits) such as knots, open checks, worm holes, along with machining and drying variations. No. 1 Common is a tasteful floor where prominent variation is expected.
No. 2 Common Oak
Contains sound natural and manufacturing variations including knot holes, open worm holes, and other open characters along with prominent color variations. Manufacturing variations include drying characters and machining irregularities. No. 2 Common is most desirable for applications where numerous notable character marks and prominent color contrast is desired.
Character Grade (Mill Run)
A blend of multiple grades that consist mainly of #1 Common and #2 Common material, with Select Grade sometimes mixed in. Also referred to as Mill Run, this is when the mill may not sort the material when being cut and simply allow the boards to be packaged randomly to show off all the natural beauty of the wood. Quality control is also used in this grade to avoid most imperfections.
No. 3 Common Oak (Utility Grade, Cabin Grade, or 2nd's)
Sometimes referred to as a Utility Grade, #3 Common will give you a very rustic looking floor with many imperfections throughout the boards. The following are admitted: shattered or rotten ends, large broken knots, excessive bad mill work, shake, advanced rot, and similar unsound defects. Dark machine burns exceeding 3/64" deep are admitted. Knotholes and open characters, which will readily fill, are admitted. Pieces with no tongue which may be face nailed are admitted. Average length of boards are usually shorter than higher grades and can even have boards below the specified range. When deciding how much is needed for a job, plan on ordering an extra amount to make up for boards that are less desirable. This means order more than than what you originally planned for cuts and leftovers during installation. Keep in mind that every person will have a different opinion for what is useable and not useable. What may be unusable or damaged to one person may be perfectly fine and useable to another. Be sure to consult your installer before purchasing.
Wondering what we mean when we say “character marks”? These are the naturally occurring features that give wood some of its character. Here are a few of the most common:
Knots are the dense, round spots that form in wood at the base of a branch or twig. In hardwood flooring, with exception of #3c and #2c, generally only “Sound” knots are permitted. Meaning that, while the grain is interrupted by the knot, the board remains smooth and no wood is actually missing from the area. Open knots will require to be filled before finishing, most likely with a common wood putty.
Streaks are generally caused by mineral deposits within a tree’s rings, though Cherry wood also sometimes displays gum streaks, an area of wood darkened by the tree’s own sap. Streaks are just what they sound like – long thin areas of the wood that are a different color from the rest due to the presence of certain minerals.
As the name suggest, these are small imperfections in the face of a board caused by worms making their way through the tree while it was alive. Generally these are no more than ¼ inch wide, though sometimes larger grubs can create virtual trenches, known as grub holes. These are typically filled with a putty, but may also be left open in some circumstances for a more rustic effect.
Plain Sawn vs Rift & Quartered vs Live Sawn (French Cut)
When lumber is cut from logs, it is typically cut in one of three ways: quarter sawn, rift sawn or plain sawn. Each type of lumber is dependent on how the log is oriented and cut at the sawmill. The result is a particular orientation of the growth rings on the end grain of the board and is what defines the type of lumber. The type of cut also determines the figure in a piece of wood and the wood’s mechanical properties.
Plain Sawn or Flat Sawn
Plain sawn, also commonly called flat sawn, is the most common lumber you will find. This is the most inexpensive way to manufacture logs into lumber. Plain sawn lumber is the most common type of cut. The annular rings are generally 30 degrees or less to the face of the board; this is often referred to as tangential grain. The resulting wood displays a cathedral pattern on the face of the board.
Quarter sawn wood has an amazing straight grain pattern that lends itself to design. Quarter sawn lumber is defined as wood where the annular growth rings intersect the face of the board at a 60 to 90 degree angle. When cutting this lumber at the sawmill, each log is sawed at a radial angle into four quarters, hence the name. Dramatic flecking is also present in red oak and white oak.
Rift sawn wood can be manufactured either as a compliment to quarter sawn lumber or logs can be cut specifically as rift sawn. In rift sawn lumber the annual rings are typically between 30-60 degrees, with 45 degrees being optimum. Manufactured by milling perpendicular to the log’s growth rings producing a linear grain pattern with no flecking. This method produces the most waste, increasing the cost of this lumber. Rift sawn lumber is very dimensionally stable and has a unique linear appearance.
Live sawn flooring, also known as French Cut, is the combination of each sawn type. This allows for slightly more stability and provides a unique graining mixture that is known well over in european homes. Typically produced in a “natural” grade (combination of all grades) which allows for some knots and natural wood characteristics and color variations, this cut helps offer a beautiful antique designed floor.