Douglas Fir (Pseudotsuga menziesii)

Woods to Know

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Douglas Fir (Pseudotsuga menziesii)



There is only one species of Douglas fir found in Canada, though it occurs in two forms. The Coast form grows along the west coast of mainland BC and on Vancouver Island. These are the classic towering giants of the west coast. A variant grows in central BC and the southwestern part of Alberta. These inland firs are smaller, seldom reaching the 300 plus foot height of the coastal firs.

Characteristics
Typically the heartwood is of a reddish brown, and the sapwood is a light rosy colour, darkening with exposure to UV rays. The wood is generally straight, though it is sometimes wavy grained, and has a medium to fairly coarse texture. There can be quite a bit of variation in the colour, weight and strength of the wood, particularly between old growth trees and second or third growth trees. Over time the wood tends to redden with exposure to sunlight.


Douglas Fir
 
Working Properties
The tough fibre of Douglas fir makes it somewhat difficult to work with hand tools, so it's important to keep tools sharp. The same goes for power tools. With sharp blades it machines to a smooth, glossy surface. It glues well, and as for most lumber, pre-drilling before screwing is recommended. It takes stain and all types of finish well. Douglas fir is a resinous wood and the resin canals can occasionally leak and bleed, marking the wood with tiny lines most visible on longitudinal surfaces.
 

Physical Properties
Douglas fir is very dimensionally stable and has a moderate resistance to shock, high stiffness and crushing strength, and high bending strength. It takes well to lamination but isn't recommended for steam bending. At 12% moisture content it has a specific gravity of .50 and a weight of around 33 pounds per cubic foot.
 
Uses
The predominant use of Douglas fir is in the pulp industry, and construction and building products: lumber, plywood, doors, studding, roof trusses, floor and ceiling joists, window frames, laminated beams, and general millwork. Nonetheless, it makes a wonderful wood for furniture and fine cabinetry. It also makes an excellent secondary wood (such as interior framework, drawer parts, dust panels and back panels). When quarter-sawn to expose its vertical grain Douglas fir is especially attractive. It is available in a wide range of dimensions, and in plywood and veneer form. Pricing is about $5.00 per board foot.


Shrinkage (These figures are for Coastal Fir) 
Moisture Content0%6%20%
Tangential 7.65.52.5
Radial4.83.01.4
Volumetric12.4n/an/a
Photo courtesy of The Wood Database