Wood species
White oak wood
White oak is a hardwood; this page covers the white oak group, led by white oak (Quercus alba). At 12% moisture content it has a Janka hardness of 1,360 lbf (6,050 N) and it weighs about 48 lb/ft³ (762 kg/m³), 4 lb (1.8 kg) per board foot.
Names and species on this page: bur oak, chestnut oak, post oak, overcup oak, swamp chestnut oak, swamp white oak, live oak.
Key numbers
- Janka hardness, 12% MC
- 1,360 lbf (6,050 N)
- Green: 1,060 lbf (4,715 N)
- Weight at 12% MC
- 48 lb/ft³ (762 kg/m³)
- 4 lb per board foot
- Specific gravity (oven-dry weight)
- 0.68 at 12% MC volume
- 0.60 on green volume
- Shrinkage, green to oven-dry
- 10.5% tangential
- Radial 5.6%, volumetric 16.3%
One source: USDA Forest Products Laboratory, the authority for species properties it measured
Why: Measured by the USDA Forest Products Laboratory; white oak's density is worked from its specific gravity with the Handbook's own equation.
How much white oak moves
A 12 in wide flatsawn board of white oak that goes from 6% to 12% moisture content swells about 0.27 in (about 9/32 in, 6.9 mm). Quartersawn, the same board moves about 0.14 in (about 1/8 in, 3.5 mm). Flatsawn faces move 1.9 times as much as quartersawn ones, because the wood shrinks 10.5% around the growth rings but only 5.6% across them.
Worked with the Wood Handbook's dimensional change coefficients for white oak (Table 13-5: 0.00376 tangential, 0.00194 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
- Generally grayish-brown heartwood; nearly white sapwood 1 to 2 in. wide.
- Grain and texture
- Heartwood pores are usually plugged with tyloses, which make the wood nearly impervious to liquids; quartersawn faces show broad rays.
- Working and character
- Somewhat heavier than red oak, with good decay resistance in the heartwood.
- Uses
- Tight barrels (cooperage), boat planking and bent parts, furniture, flooring, doors and millwork.
The Handbook groups live oak with the tropical oaks in Chapter 2 but tables it beside the white oaks; it is shown here as a row of its own.
Adapted in our own words from the Wood Handbook, Chapter 2, p. 2-9.
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE). Clear, straight-grained samples of white oak 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) | 8,300 psi (57 MPa) | 15,200 psi (105 MPa) |
| Stiffness (MOE) | 1,250,000 psi (8.6 GPa) | 1,780,000 psi (12.3 GPa) |
| Crushing strength (compression parallel to grain) | 3,560 psi (25 MPa) | 7,440 psi (51 MPa) |
| Compression perpendicular to grain | 670 psi (5 MPa) | 1,070 psi (7 MPa) |
| Shear parallel to grain | 1,250 psi (9 MPa) | 2,000 psi (14 MPa) |
| Tension perpendicular to grain | 770 psi (5 MPa) | 800 psi (6 MPa) |
A dash means the Handbook prints no value; none is filled in.
The white oak group
The Handbook tests each species separately; they are sold together as white oak. Across the 7 species measured, Janka hardness at 12% runs from 1,130 to 1,620 lbf.
| Species | Janka, 12% MC | Weight, 12% MC | Tangential shrinkage |
|---|---|---|---|
| White oakQuercus alba | 1,360 lbf | 48 lb/ft³ | 10.5% |
| Bur oakQuercus macrocarpa | 1,370 lbf | 45 lb/ft³ | 8.8% |
| Chestnut oakQuercus montana | 1,130 lbf | 46 lb/ft³ | 10.8% |
| Live oakQuercus virginiana | — | 62 lb/ft³ | 9.5% |
| Overcup oakQuercus lyrata | 1,190 lbf | 44 lb/ft³ | 12.7% |
| Post oakQuercus stellata | 1,360 lbf | 47 lb/ft³ | 9.8% |
| Swamp chestnut oakQuercus michauxii | 1,240 lbf | 47 lb/ft³ | 10.8% |
| Swamp white oakQuercus bicolor | 1,620 lbf | 50 lb/ft³ | — |
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 white oak at 1,360 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 × 0.68 × 1.12.
Arithmetic: exact by definition , sources [1]
The number
About 48 lb/ft³, or 4 lb per board foot (1/12 ft³), at 12% moisture content.
Arithmetic: exact by definition
Sources