Lumber Grade Rules

Lumber Grade Rules


This chart summarizes the main requirements for the standard grades. For complete information, consult the appropriate section of the NHLA Rule Book.

#1 COM
#2 & 2B
Minimum Size Board
6″ x 8′
Same as FAS for species being graded
4″ x 6′
3″ x 4′
3″ x 4′
3″ x 4′
3″ x 4′
PITH= SM in inchesWane= 1/2 Length Knot= 1/3 SM Warp= Entire board must be flat enough to S2S to S.S.T. Splits: not to exceed 2 x SM or 12″ whichever is greater. Splits shall not diverge 1″ in 12″ First Lineal Foot Rule: Applies to both ends of Board, to contain not over 25% unsound wood.
Wane in FASIFACE: FAS transmission applies to better face.#1 Common Side: 1/3W or 1/2L Widest wane added together: Length can be on both edges.
Minimum Size Cutting
4″ x 5′ 3″ x 7′
4″ x 2′ 3″ x 3′
3″ x 2′
3″ x 2′
Not less than 1 1/2″ wide containing 36 sq. inches
Wane in Selects: Pcs. 6″ & Wider FAS limitation applies to Better face.#1 Common side: 1/3W or 1/2L Widest wane added together. Length can be on both side. Pcs. 4″ & 5″ Wide 1/3W or 1/2L applies to both faces. Add widest wane together. Add total length of wane from both edges.
Basic Yield
SM x 10 83-1/3%
SM x 8 60-2/3%
SM x 6 50%
SM x 4 33-1/3%
SM x 3 25%
Formula to Determine Number of Cuts
SM ——– 4 (4 max.)
SM+1 ——– 3 (5 max.)
SM ——– 2 (7 max.)
Unlimited Sound Cuttings
SM Needed to Take Extra Cutting
6-15′ SM
3-10′ SM
2-7′ SM
Extra Yield Needed for Extra Cutting
SM x 11 91-2/3%
SM x 9 75%
SM x 8 66-2/3%
Special Yields
97% Rule -2 cuts full width any length; Pcs. 6″ & wider with 6-12″ SM SM x 11.64 for Yield
97% Rule On Better Face
2 + 3 SM to be 100% clear or SM x 11 in one cutting on Better Face. 97% Rule
1′ SM-100% 2′ SM SMx 9
1′ SM SMx 8 2A Com- Clear Face Cuttings 2B Com- Sound Cuttings
2A Com on Better Face and reverse side of cuttings sound; will also qualify for 3A Com
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