Wood species
Lodgepole pine wood
Lodgepole pine is a softwood (Pinus contorta). At 12% moisture content it has a Janka hardness of 480 lbf (2,135 N) and it weighs about 29 lb/ft³ (459 kg/m³), 2.4 lb (1.08 kg) per board foot.
Also called: knotty pine, black pine.
Key numbers
- Janka hardness, 12% MC
- 480 lbf (2,135 N)
- Green: 330 lbf (1,468 N)
- Weight at 12% MC
- 29 lb/ft³ (459 kg/m³)
- 2.4 lb per board foot
- Specific gravity (oven-dry weight)
- 0.41 at 12% MC volume
- 0.38 on green volume
- Shrinkage, green to oven-dry
- 6.7% tangential
- Radial 4.3%, volumetric 11.1%
One source: USDA Forest Products Laboratory, the authority for species properties it measured
Why: Measured by the USDA Forest Products Laboratory; lodgepole pine's density is worked from its specific gravity with the Handbook's own equation.
How much lodgepole pine moves
A 12 in wide flatsawn board of lodgepole pine that goes from 6% to 12% moisture content swells about 0.19 in (about 3/16 in, 4.8 mm). Quartersawn, the same board moves about 0.13 in (about 1/8 in, 3.2 mm). Flatsawn faces move 1.6 times as much as quartersawn ones, because the wood shrinks 6.7% around the growth rings but only 4.3% across them.
Worked with the Wood Handbook's dimensional change coefficients for lodgepole pine (Table 13-5: 0.00263 tangential, 0.00176 radial per 1% change in moisture content), which hold between 6% and 14%. Individual boards vary: the Handbook gives shrinkage a coefficient of variation of about 15% (p. 4-11).
Color, grain and working
- Color
- Light yellow to light yellow-brown heartwood; yellow or nearly white sapwood.
- Grain and texture
- Generally straight, with narrow growth rings.
- Working and character
- Moderately light and fairly easy to work, with fairly high shrinkage; moderately soft and fairly weak.
- Uses
- Framing, siding, millwork, flooring, cabin logs, poles and mine timbers.
Adapted in our own words from the Wood Handbook, Chapter 2, p. 2-14.
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE). Clear, straight-grained samples of lodgepole pine tested by the Forest Products Laboratory (Wood Handbook Table 5-3b). Knots and cross grain make lumber weaker than these clear samples (Handbook Chapter 5).
| Property | Green | 12% MC |
|---|---|---|
| Bending strength (MOR) | 5,500 psi (38 MPa) | 9,400 psi (65 MPa) |
| Stiffness (MOE) | 1,080,000 psi (7.4 GPa) | 1,340,000 psi (9.2 GPa) |
| Crushing strength (compression parallel to grain) | 2,610 psi (18 MPa) | 5,370 psi (37 MPa) |
| Compression perpendicular to grain | 250 psi (2 MPa) | 610 psi (4 MPa) |
| Shear parallel to grain | 680 psi (5 MPa) | 880 psi (6 MPa) |
| Tension perpendicular to grain | 220 psi (2 MPa) | 290 psi (2 MPa) |
A dash means the Handbook prints no value; none is filled in.
Dust and health
- Wood dust is classed as carcinogenic to humans (Group 1) by the International Agency for Research on Cancer, chiefly for cancers of the nose and sinuses.
- NIOSH recommends keeping wood dust exposure to 1 mg/m³ of total dust, as quoted in OSHA's sawmill guidance.
This is what the named authorities publish, not medical advice.
Compare with
Why these numbers
Why these numbers?
The situation
The USDA Forest Products Laboratory measured lodgepole pine at 480 lbf of side hardness at 12% moisture content, on clear, straight-grained samples (Wood Handbook Table 5-3b).
One source: USDA Forest Products Laboratory, the authority for species properties it measured , sources [1]
What that means
Side hardness (Janka) is the load needed to press a 0.444 in (11.28 mm) steel ball halfway into the wood across the grain; a higher number dents less (Handbook p. 5-5).
One source: USDA Forest Products Laboratory, the authority for species properties it measured , sources [1]
So
Density at 12% is water's density × specific gravity × (1 + 0.12) (Handbook Eq. 4-14): 62.43 × 0.41 × 1.12.
Arithmetic: exact by definition , sources [1]
The number
About 29 lb/ft³, or 2.4 lb per board foot (1/12 ft³), at 12% moisture content.
Arithmetic: exact by definition
Sources