Douglas fir is one of the worlds most important timber woods due to its very large size and because it is very heavy, dense, strong, and yet easy to work with. It is a highly valued wood for building exterior structures because it is almost knot-free and can be sawn to great lengths. It is ofter used for exterior structures such as pergolas, telephone wire poles and railway sleepers. The color of Douglas fir is typically yellow-red, faint red, or a pinkish brown color. It is one of the most structurally sound soft woods available. A domestic wood, Douglas Fir is commonly used for veneers, plywood, and structural/construction lumber. Douglas fir was named after the scientist David Douglas. It is sometimes used as a Christmas tree even though it has to be sheared to a pyramidal shape.
Species: Pseudotsuga menziesii
Other names: Fir, Spruce-pine-fir (SPF), Big Cone Fir, coast Douglas-fir (P. menziesii var. menziesii), and Rocky Mountain Douglas-fir (P. menziesii var. glauca).
|Douglas Fir Origin: Canada (Alberta, British Columbia); Mexico (Coahuila, Colima, Durango, Hidalgo, Puebla, Sinaloa, Sonora, Zacatecas); United States (Arizona, California, Colorado, Idaho, Minnesota, Nevada, New Mexico, Oregon, Texas, Utah, Washington, Wyoming)
Appearance: Douglas fir is a yellowish, light brown colored wood with a straight plain grain, except in flatsawn pieces, where the grain is in wild patterns.
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 lbf (2,760 N)
Modulus of Rupture: 12,500 lbf/in2 (86.2 MPa)
Elastic Modulus: 1,765,000 lbf/in2 (12.17 GPa)
Crushing Strength: 6,950 lbf/in2 (47.9 MPa)
Shrinkage: Radial: 4.5%, Tangential: 7.3%, Volumetric: 11.6%, T/R Ratio: 1.6
Color/Appearance: The color is very dependent on the age and location of the tree. The color of Douglas fir ranges from light brown color to reddish or yellowish brown with darker growth rings. The grain depends on the grade of the Douglas fir bought with A grade being typically straight and plain
Drying: The drying method depends on the size of the wood. Any wood that is 1” in width (such as that used for siding) will be kiln dried. Any lumber that is over 2” wide will be air dried.
Sustainability: The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) does not list Douglas fir in its appendices. The International Union for Conservation of Nature’s Red List of Threatened Species (IUCN) list Douglas fir as a species of least concern.
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