Douglas Fir (Pseudotsuga menziesii)

Information provided by Wood Database

Common Name(s): Douglas-Fir, Doug Fir, DF

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: 32 lbs/ft³ (510 kg/m³)

Specific Gravity (Basic, 12% MC): .45, .51

Janka Hardness: 620 lb_f (2,760 N)

Modulus of Rupture: 12,500 lb_f/in² (86.2 MPa)

Elastic Modulus: 1,765,000 lb_f/in² (12.17 GPa)

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. In quartersawn pieces, the grain is typically straight and plain. In flatsawn pieces, (typically seen in rotary-sliced veneers), the wood can exhibit wild grain patterns.

Grain/Texture: Grain is generally straight, or slightly wavy. Medium to coarse texture, with moderate natural luster.

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.

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

Douglas Fir Grade Description**

Clear – Has no Knots

Select or Select Structural – Very High-quality wood. Sound Firm, encased and pith knots are to be tight, well-spaced and limited up to 7/8”. Un sound or loose knots or holes are limited up to ¾”. One per 4’ lineal.

#1 common – Knots must be of same type as SelStr grade, but up to 1-1/2”. Unsound or loose knots or holes are limited up to 1”. One per 3’ lineal. Wane is allowable.

#2 common – Well-spaced Knots of any quality up to 2”, with one hole up to 1-1/4” per 2’ lineal. Wane & skips are included.

#3 common – Knots of any quality can be up to 2-1/2”, with one hole up to 1-3/4” per lineal foot. Wane & skips are included

Construction/Standard – Good strength; used for general framing.

Utility – Economy grade used for rough Framing.

Appearance Grade – strictly sold on appearance. Knots, strength and other characteristics have no requirements.