Douglas Fir

Scientific name:
Pseudotsuga menziesii

Other names:

Oregon Pine

British Columbian Pine

Red Fir

Douglastree

The massive, fine grained Douglas firs, which grow in abundance along Canada’s west coast provided British Columbia’s very first cargoes of export lumber as long ago as 1865. Yet over 75 percent of the Douglas fir harvested today is still fine grained timber, characterized by exceptional strength, hardness and durability. The tree has a long, straight trunk with very little taper, and in heavy stands is free of branches for two-thirds or more of its height, yielding a high percentage of clear and near-clear wood in long lengths and large sizes.

Weight:

Standard Specific Gravity 0.45 (12% M.C.); Density: green 450 kg/m³ /air dry 487 kg/m³

Use:

Foundation stud and plywood walls, vehicular bridges, walkways, parks shelters and foot bridges, concealed framing, exposed roof beams and rafters or fascias, barges, pergolas and other external structures.

General characteristic:

Douglas Fir’s light rosy color is set off by its remarkably straight and handsome grain pattern. It is more widely available in the appearance grades. Douglas fir is the only redwood-type material still available in substantial volumes of clear wood fiber.

It is combined with dense grain structure and fine texture – gives this wood exceptional versatility. It is highly regarded and widely specified both for the most demanding structural applications and for joinery and architectural millwork of the best quality.

Working properties:

Douglas-fir has excellent strength properties and is well known for its workability. The wood dries rapidly with small dimensional movement and little tendency to check. It is relatively easy to work, with good machining qualities. It turns, planes and shapes well and can be sanded to a smooth finish. The wood glues moderately easily, has moderate nail and good screw holding ability, and takes a good finish

Drying and shrinkage:

Douglas Fir is dried in temperature and humidity-controlled kilns or stacked and air dried until its moisture content (MC) reaches the desired level for an intended purpose. Douglas-fir lumber is dried according to end-use and customer specifications.

Radial (OD) 4.8%; Tangential (OD) 7.4%; Volumetric (OD) 11.9%; Volumetric (air) 7.0%

Durability:

Douglas fir is suitable for many fully or partly weather exposed structures. However, because it is not rated as a highly durable timber, Douglas fir should not be used in some external structural applications such as bearers and joists under weather exposed decks. When used in pergolas, the framing should be attached to the building rather than forming a continuation of the main building roof structure. All weather exposed Douglas fir should be well primed, finished and maintained.

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