Rules & Regulations of the State of Tennessee
Title 0080 - Department of Agriculture
Subtitle 0080-07 - Forestry
Chapter 0080-07-07 - Native Species Lumber
Section 0080-07-07-.04 - SPECIFICATIONS

Universal Citation: TN Comp Rules and Regs 0080-07-07-.04

Current through September 24, 2024

(1) Characteristics allowed and limiting provisions:

(a) Knots:
1. The size of a knot is measured directly as the diameter (in inches) for a round knot, and for other than round knots (e.g., spike knots and oval knots) the equivalent diameter size is estimated by averaging the measurements (in inches) of the maximum width of the knot on its narrow axis and the maximum length on its long axis.

2. Sound, firm, and encased knots, if tight and well-spaced, are permitted in sizes not to exceed the equivalent of 25% of the nominal width of the wide face of the piece. Knots appearing on the thickness faces of the piece are permitted in the same quality and size shown on Table 1.

3. A sound knot contains no decay.

4. A firm knot is solid across its face but has incipient decay.

5. An encased knot is a knot, which is not intergrown with the growth rings of the surrounding wood.

6. A tight knot is so fixed by growth, shape, or position that it retains its place or is held in place in the piece, while a loose knot or a not firmly fixed knot is one which is not so fixed by growth, shape or position that it will not be held tightly in place in the piece.

7. Well-spaced knots mean that the sum of the sizes of knots in any 6-inch length cannot equal or exceed twice the size of the largest permitted knot.

(b) Holes:
1. A hole may extend completely or partially through the piece.

2. Hole sizes are measured as knots are. Holes are caused by unsound wood except wane, unsound knots, loose knots, and not firmly fixed knots.

3. Holes are not to exceed the equivalent of 25% of the nominal width of the piece or equivalent smaller holes per 2 lineal feet.

4. Holes appearing on the thickness faces of the piece including unsound wood except wane, unsound knots, loose knots, and not firmly fixed knots are permitted in the same size or equivalent smaller as shown in Table 1.

Table 1 Knot and Hole Limits

Nominal Width of Lumber

Knot or Hole Maximum Size or Equivalent

(Inches)

(Inches)

2

1/2

2 1/2

5/8

3

3/4

3 1/2

7/8

4

1

4 1/2

1 1/8

5

1 1/4

6

1 1/2

8

2

10

2 1/2

12

3

Knots: sound, firm, encased & pith knots if tight and well-spaced

Holes: includes all unsound wood, except wane and unsound or loose knots

(c) Unsound wood, except wane, is not permitted.

(d) Wane of 1/3 the thickness and 1/3 the width, full length, or equivalent, on each face, combined is not to exceed 1/2 the thickness or 1/2 the width at any point.

(e) Shakes on the surface can occur on only one surface of the piece of lumber.

(f) The slope of grain deviation is expressed as a ratio of the deviation over the length. For example, for 1 in 8 slope in grain there is 1 inch in deviation between the grain of the wood and the lumber's edge for every 8 inches of length.

(g) Shake through at ends are limited as splits. Away from ends, shakes including through shakes up to 2 feet long are permitted.

(h) Splits are limited in the length to twice the width of the piece.

(i) Checks - Drying checks on the face or edge are not limited.
1. Through checks at end are limited as splits. Surface checks occur on a wide or thickness face of a piece.

2. A through check will extend from one surface face to an opposite or adjoining surface.

3. A through shake will extend from one surface face to an opposite or adjoining surface.

(j) Warp limits are included in Table 2.

Table 2 Warp Limits

Twist

Lumber Nominal Width (Inches)

Lumber Length (Feet)

2

3 & 4

5 & 6

8

10

12 +

Twist Limit (Inches)

6

1/8

1/4

3/8

1/2

5/8

3/4

8

1/4

1/2

3/4

1

1 1/4

1 1/2

10

5/16

5/8

7/8

1 1/4

1 1/2

1 7/8

12

3/8

3/4

1 1/4

1 1/2

1 7/8

2 1/4

14

7/16

7/8

1 1/4

1 3/4

2 1/4

2 5/8

16+

1/2

1

1 1/2

2

2 1/2

3

Crook

Lumber Nominal Width (Inches)

Lumber Length (Feet)

2

3 & 4

5 & 6

8

10

12 +

Crook Limit (Inches)

6

1/4

1/4

3/16

1/8

1/16

1/16

8

3/8

3/8

5/16

1/4

3/16

1/8

10

3/4

1/2

7/16

3/8

1/4

3/16

12

1

11/16

5/8

1/2

7/16

3/8

14

1 1/4

7/8

3/4

5/8

1/2

3/8

16+

1 5/8

1

7/8

3/4

5/8

1/2

Cup

Lumber Nominal Width (Inches)

2

3 & 4

5 & 6

8

10

12 +

Cup Limit (Inches)

All lengths

1/16

1/16

1/16

1/4

3/16

1/4

Bow

Lumber Nominal Thickness (Inches)

Lumber Length (Feet)

2

3 & 4

Bow Limit (Inches)

6

1/2

1/4

8

3/4

3/8

10

1 1/2

3/4

12

2

1

14

2 1/2

1 1/4

16+

3 1/4

1 5/8

(k) Twists are measured as the point of distance that the edge of a piece is raised above a flat surface where both edges of the opposite end of the same piece are resting against the same flat surface. Limits are included in Table 2.

(l) Manufacturing defects not greater than 1/8th inch are permitted

(m) Pitch and pitch streaks are permitted.

(n) Pockets, pitch or bark, are not limited.

(o) Stains are not limited.

(p) Surfaced lumber may have skips or scant in places up to 1/8 inch deep. If it is rough lumber, there may be scant in places up to 1/8 inch scant. The areas of skip or scant are not to exceed 2 feet in length in any one place.

(q) Lumber included in the Tennessee Native species lumber Number 2 and Better Grade is to reasonably represent the mill-run of dimension lumber produced at least meeting these requirements and limiting provisions, without sort-out removal of higher-grade dimension lumber. This is not to constrain the simultaneous production of appearance grade boards and other lumber products other than dimension.

Authority: T.C.A. §§ 4-3-203 and 43-28-313.

Disclaimer: These regulations may not be the most recent version. Tennessee may have more current or accurate information. We make no warranties or guarantees about the accuracy, completeness, or adequacy of the information contained on this site or the information linked to on the state site. Please check official sources.
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