Wood species
Grand fir wood
Grand fir is a softwood (Abies grandis). At 12% moisture content it has a Janka hardness of 490 lbf (2,180 N) and it weighs about 26 lb/ft³ (414 kg/m³), 2.2 lb (0.98 kg) per board foot.
Also called: Abies grandis.
Key numbers
- Janka hardness, 12% MC
- 490 lbf (2,180 N)
- Green: 360 lbf (1,601 N)
- Weight at 12% MC
- 26 lb/ft³ (414 kg/m³)
- 2.2 lb per board foot
- Specific gravity (oven-dry weight)
- 0.37 at 12% MC volume
- 0.35 on green volume
- Shrinkage, green to oven-dry
- 7.5% tangential
- Radial 3.4%, volumetric 11.0%
One source: USDA Forest Products Laboratory, the authority for species properties it measured
Why: Measured by the USDA Forest Products Laboratory; grand fir's density is worked from its specific gravity with the Handbook's own equation.
How much grand fir moves
A 12 in wide flatsawn board of grand fir 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 0.08 in (about 3/32 in, 2.1 mm). Flatsawn faces move 2.2 times as much as quartersawn ones, because the wood shrinks 7.5% around the growth rings but only 3.4% across them.
Worked with the Wood Handbook's dimensional change coefficients for grand fir (Table 13-5: 0.00263 tangential, 0.00116 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
- Creamy white to pale brown, like the other true firs.
- Working and character
- A western true fir: light in weight, somewhat stronger than balsam fir, with low to moderately high shrinkage.
- Uses
- Western true firs are sold as white fir for framing, subflooring, sheathing, boxes, sashes, doors and millwork.
The Handbook says the true firs cannot be told apart by their wood alone.
Adapted in our own words from the Wood Handbook, Chapter 2, p. 2-12.
Strength
Bending strength is the modulus of rupture (MOR); stiffness is the modulus of elasticity (MOE). Clear, straight-grained samples of grand fir 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) | 5,800 psi (40 MPa) | 8,900 psi (61 MPa) |
| Stiffness (MOE) | 1,250,000 psi (8.6 GPa) | 1,570,000 psi (10.8 GPa) |
| Crushing strength (compression parallel to grain) | 2,940 psi (20 MPa) | 5,290 psi (36 MPa) |
| Compression perpendicular to grain | 270 psi (2 MPa) | 500 psi (3 MPa) |
| Shear parallel to grain | 740 psi (5 MPa) | 900 psi (6 MPa) |
| Tension perpendicular to grain | 240 psi (2 MPa) | 240 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 grand fir
Work it out for your project
- Rank woods for cabinets and trim with the species picker
Weigh grand fir against other woods on hardness, weight, movement and color, every figure from the Wood Handbook.
- Plan a finish for cabinets in grand fir
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 grand fir at 490 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 × 0.37 × 1.12.
Arithmetic: exact by definition , sources [1]
The number
About 26 lb/ft³, or 2.2 lb per board foot (1/12 ft³), at 12% moisture content.
Arithmetic: exact by definition
Sources