Wood species
Engelmann spruce wood
Engelmann spruce is a softwood (Picea engelmannii). At 12% moisture content it has a Janka hardness of 390 lbf (1,735 N) and it weighs about 24 lb/ft³ (392 kg/m³), 2 lb (0.93 kg) per board foot.
Also called: mountain spruce, Arizona spruce, silver spruce, Picea engelmannii.
Key numbers
- Janka hardness, 12% MC
- 390 lbf (1,735 N)
- Green: 260 lbf (1,157 N)
- Weight at 12% MC
- 24 lb/ft³ (392 kg/m³)
- 2 lb per board foot
- Specific gravity (oven-dry weight)
- 0.35 at 12% MC volume
- 0.33 on green volume
- Shrinkage, green to oven-dry
- 7.1% tangential
- Radial 3.8%, volumetric 11.0%
One source: USDA Forest Products Laboratory, the authority for species properties it measured
Why: Measured by the USDA Forest Products Laboratory; Engelmann spruce's density is worked from its specific gravity with the Handbook's own equation.
How much Engelmann spruce moves
A 12 in wide flatsawn board of Engelmann spruce that goes from 6% to 12% moisture content swells about 0.18 in (about 3/16 in, 4.5 mm). Quartersawn, the same board moves about 0.09 in (about 3/32 in, 2.4 mm). Flatsawn faces move 1.9 times as much as quartersawn ones, because the wood shrinks 7.1% around the growth rings but only 3.8% across them.
Worked with the Wood Handbook's dimensional change coefficients for Engelmann spruce (Table 13-5: 0.00248 tangential, 0.0013 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
- Nearly white heartwood with a slight tinge of red; the 1 to 2 in. of sapwood is often hard to tell from it.
- Grain and texture
- Medium to fine texture, no characteristic odor; the lumber usually has many small knots.
- Working and character
- Lightweight, soft, low in strength as a beam or post, and low in stiffness, shock resistance and shrinkage.
- Uses
- Lumber, mine timbers, crossties and poles; dimension lumber, flooring and sheathing; and excellent for pulp and paper.
Adapted in our own words from the Wood Handbook, Chapter 2, p. 2-18.
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE). Clear, straight-grained samples of Engelmann spruce 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) | 4,700 psi (32 MPa) | 9,300 psi (64 MPa) |
| Stiffness (MOE) | 1,030,000 psi (7.1 GPa) | 1,300,000 psi (9 GPa) |
| Crushing strength (compression parallel to grain) | 2,180 psi (15 MPa) | 4,480 psi (31 MPa) |
| Compression perpendicular to grain | 200 psi (1 MPa) | 410 psi (3 MPa) |
| Shear parallel to grain | 640 psi (4 MPa) | 1,200 psi (8 MPa) |
| Tension perpendicular to grain | 240 psi (2 MPa) | 350 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
Buying and finishing Engelmann spruce
Work it out for your project
- Rank woods for flooring with the species picker
Weigh engelmann spruce against other woods on hardness, weight, movement and color, every figure from the Wood Handbook.
- Plan a finish for a floor in engelmann spruce
The finishes whose makers name that use, and a dated coat schedule from each product’s own sheet.
Why these numbers
Why these numbers?
The situation
The USDA Forest Products Laboratory measured Engelmann spruce at 390 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 × 0.35 × 1.12.
Arithmetic: exact by definition , sources [1]
The number
About 24 lb/ft³, or 2 lb per board foot (1/12 ft³), at 12% moisture content.
Arithmetic: exact by definition
Sources