Douglas-fir

Pseudotsuga menziesii (Mirb.) Franco · Softwood · North America

Janka 710 lbf≈30 lb/ft³ dried (est.)

Properties

Janka hardness	710 lbf (3,158 N)
Average dried weight (est.)	30 lb/ft³ (480 kg/m³)
Specific gravity	0.48
Modulus of rupture	12,400 psi (85.5 MPa)
Modulus of elasticity	1.95 million psi (13.45 GPa)
Crushing strength	7,230 psi (49.9 MPa)
Shrinkage — radial	4.8%
Shrinkage — tangential	7.6%
Shrinkage — volumetric	12.4%
Shrinkage T/R ratio	1.6

Values at 12% moisture content, clear-wood averages. Source: USDA Forest Products Laboratory, Wood Handbook FPL-GTR-282 (2021), Table 5–3b p. 5–12; shrinkage Table 4–3 p. 4–8.

Douglas-fir, known locally as redfir, Douglas-spruce, or yellowfir, is a leading western construction wood used mostly as lumber, piles, and plywood. Its lumber is remanufactured into sashes, doors, laminated beams, general millwork, and railroad-car construction.

Appearance & grain

The sapwood is narrow in old-growth trees but may be as much as 7 cm (3 in.) wide in second-growth trees of commercial size. Young trees of moderate to rapid growth have reddish heartwood, sold locally as redfir, while very narrow-ringed old-growth heartwood may be yellowish brown and is marketed as yellowfir.

Workability

Douglas-fir varies widely in weight and strength, so higher-density wood should be used when high structural strength is needed. Considerable quantities nonetheless go into heavy service, from piles and railroad crossties to mine timbers and poles.