Hardwood flooring in various widths, thicknesses and grades is made from solid pieces of wood. The grade of the flooring, which refers to the number of defects allowed and the coloration of the wood, refers primarily to the flooring's appearance. The cut refers to the how the wood strips or planks were cut from the logs.
The clear grade is the top grade of the wood. The strips or planks are cut primarily from the heart of the tree with very little of the softer, outer sapwood allowed in the planks. Slight color variations are allowed along with some streaks from mineral absorption. Grade clear allows for the fewest defects from insects and worms and natural causes and has limited natural variations. Grade clear does not allow for pieces shorter than 15 inches and requires an average length of 45 inches or more in bundles of planks up to 7 feet long.
Select grade allows for a mix of hardwood and sapwood. Natural color variations due to minerals and other factors are allowed. Defects from insects and other organisms are limited, but allowable. Very few knots are allowed and no closer than 3 feet apart. Small defects or discolorations from the machining process should not affect the entire length of a strip, but may occur in limited amounts. Plank lengths range from 15 inches or more with an average length of 39 inches in bundles of strips up to 7 feet long.
No. 1 Common
No. 1 common has wide color variation and contains both heartwood and sapwood. Often, the predominance of sapwood also means an increasing number of knots. Some broken knots are allowed as long as they do not exceed 1/2 inch in diameter, but tight, unbroken knots are allowed along the length of the strips. Strip lengths are over 15 inches with an average length of 33 inches in bundles of strips 7 feet long.
No. 2 Common
No. 2 common has natural color variations, machining defects and imperfections. Wood flooring of this grade is commonly used in homes where wood with "character" is desired. Most defects are allowed as long they do not affect the usability of the product. No broken strip ends, rotted wood, defects that make the wood unsound or excessive defects caused by machining are allowed. The minimum length is 15 inches; the average length in a 7-foot-long bundle must be 27 inches or longer.
Bundles of shorts must average 15 inches in length in a bundle 18 inches long. Pieces as short as 3 inches are allowed. Shorts graded as clear, select and No. 1 common are bundled together and labeled "No. 1 Common or Better." Pieces graded as No. 2 must be bundled separately and labeled "No. 2 Common."
Lumber mills cut logs using three different sawing methods: plain sawn, quarter sawn or rift sawn. A log that is plain sawn is simply cut into planks, beginning on one side of the log and proceeding to the other side. A quarter-sawn log is cut into quarters. Each board cut from the quarter is cut perpendicular to the outside of the log. This results in a vertical orientation of the grain in each board with respect to the face of the wood. Rift sawn boards have the grain at an approximate 45-degree angle to the face of the board.
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