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**

All lumber grades in all species allow a certain number of defects in restricted sizes. in every grade limited variations exist for characteristics such as Checks, cracks, wane knots, pitch splits and more. For a detailed description of the allowable defects and strength properties refer to the PLIB website for more information.

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”. Unsound 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/Exposed Grade – Non-engineered lumber is a natural product that will inherently contain a number of natural defects. "Appearance" or "Exposed" material is graded visually and may contain structural defects that are acceptable in a "pretty board". Appearance grades are not regulated by the WCLB & PLIB and are "in the eye of the beholder". Therefore, requests of this type are carried out to the mills "best ability" and not guaranteed to match customer standards. Appearance grading is done as a courtesy. Strictly sold on appearance, Knots, strength, wane and other characteristics have no requirements.