Douglas-Fir

Douglas-Fir (Pseudotsuga menziesii)

Common Name(s): Douglas-Fir

Scientific Name: Pseudotsuga menziesii

Distribution: Western North America

Tree Size: 200-250 ft (60-75 m) tall, 5-6 ft (1.5-2 m) trunk diameter

Average Dried Weight: 36 lbs/ft³ (570 kg/m³)

Basic Specific Gravity: .45

Hardness: 620 lb_f (2,760 N)

Rupture Strength: 12,500 lb_f/in² (86,200 kPa)

Elastic Strength: 1,765,000 lb_f/in² (12,170 MPa)

Crushing Strength: 6,950 lb_f/in² (47.9 MPa)

Shrinkage: Radial: 4.5%, Tangential: 7.3%, Volumetric: 11.6%, T/R Ratio: 1.6

Color/Appearance: Can vary in color based upon age and location of tree. Usually a light brown color with a hint of red and/or yellow, with darker growth rings.

Grain/Pore: In quartersawn pieces, the grain is typically straight and plain. In flatsawn pieces, (typically seen in rotary-sliced veneers), the grain can be figured and irregular. Occasionally may be seen with a decorative curly or wavy grain.

Endgrain: Small to medium sized resin canals, infrequent and variable in distribution; solitary or in tangential groups of several; earlywood to latewood transition abrupt, color contrast high; tracheid diameter medium-large.

Durability: Douglas-Fir heartwood is rated to be moderately-durable in regard to decay, but is susceptible to insect attack.

Workability: Typically machines well, but has a moderate blunting effect on cutters. Accepts stains, glues, and finishes well.

Scent: Has a distinct, resinous odor when being worked.

Safety: Although severe reactions are quite uncommon, Douglas-Fir has been reported to cause skin irritation, nausea, giddiness, along with an increased likelihood of splinters getting infected. See the articles Wood Allergies and Toxicity and Wood Dust Safety for more information.

Price/Availability: Should be widely available as construction lumber for a modest price. Old growth or reclaimed boards can be much more expensive.

Comments: Douglas-Fir is technically not a true Fir (Abies genus), but is in its own genus: Pseudotsuga. It is an incredibly valuable commercial timber, widely used in construction and building purposes. The tree itself grows to be very large, and yields a large amount of usable lumber and veneer for plywood.

Douglas-Fir is very stiff and strong for its weight, and is also among the hardest and heaviest softwoods. The mechanical properties above were taken and averaged from four regions: Coastal, Interior West, Interior North, and Interior South.