Photo credit: Kirstin Charleton, Sundew Media
Douglas-fir is a large tree, reaching 85 metres on B.C.’s coast and 42 metres in the Interior. The oldest trees can be more than 1,500 years old. Due to its strength, Douglas-fir is used for building and construction, and it is one of the finest timbers for heavy structural purposes, including glue-laminated timber (glulam) beams and roof trusses.
There are two varieties of Douglas-fir in B.C.: coastal and interior. The coastal variety (var. menziesii) is found along the southern mainland coast and across Vancouver Island, except for the very northern tip. The interior variety (var. glauca) occurs throughout southern B.C. and as far north as Takla Lake near the Yukon border.
Douglas-fir grows in pure, even-aged stands, usually after wildfires; in uneven-aged stands; and in a number of mixed-species stands. The two varieties are found in quite different environments. Interior Douglas-fir can be found in a range of habitats including open forests with pinegrass and moss understory. On the coast, forests are more productive and Douglas-fir grows in mixed stands of western red cedar, hemlock and grand fir.
Did you know?
The common name for Douglas-fir is hyphenated because it is not a true fir. Because of its similarity to other species, it has been called pine, spruce, hemlock and true fir. In 1867, it was given its own genus—Pseudotsuga—which means false hemlock.
Douglas-fir is a large tree, reaching 85 metres on the west coast and 42 metres in the interior. Commonly living to be at least 500 years of age, the oldest trees can be more than 1,500 years old. Older trees have a long, branch-free trunk and a short cylindrical crown with a flattened top.
Young Douglas-fir bark is smooth and grey-brown with gummy resin-filled blisters. The bark becomes very thick and deeply grooved with age, growing dark reddish-brown ridges.
Needles are flat with a pointed tip. The upper surface is bright yellowish-green with a single groove down the centre; the lower surface is paler. The needles appear to stand out around the twig. Cones are 5 to 11 centimetres long, turning from green to grey as they mature. Three-pronged flowers are visible between each scale. Seeds are winged at the tip.
Photo credit: Kristin Charleton, Sundew Media
Due to its strength, Douglas-fir is primarily used for building and construction. It is hard and resistant to abrasion, making it suitable for uses where wear is a factor, such as wharves, trestles, bridge parts, log homes and commercial buildings. It is one of the finest timbers for heavy structural purposes, including glulam beams and roof trusses.
Douglas-fir is a high-quality wood for the manufacturing of sashes, doors and windows. It is also used to produce a wide variety of products including general millwork, flooring, furniture, cabinets, veneer, vats, ships and boats, transmission poles and marine pilings.
Indigenous Peoples in B.C. have many uses for Douglas-fir, including pit cooking fuel, fishing hooks and handles. They also use Douglas-fir boughs for covering the floors of lodges and sweat lodges.
The Land is a Person, sculpture by Marianne Nicolson | Photo courtesy of Barker Manufacturing Inc.
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.
The sapwood is narrow in width and light in colour. The heartwood ranges from yellowish to reddish-brown. Earlywood and latewood have a pronounced difference in colour—latewood has darker, more sharply defined bands. This colour difference results in a distinctive grain pattern when flat-sawn. The wood has a fine to medium texture and straight grain and is non-porous.
Coastal Douglas-fir is a much bigger tree than the interior species, and it is generally lighter in colour with a more uniform texture. Both have the same wood properties, although interior Douglas-fir is less permeable to preservative treatments.
Surrey Central City | Photo credit: Nic Lehoux
Douglas-fir is marketed predominantly as Douglas-fir-Larch in structural grades according to National Lumber Grades Authority (NLGA) rules for dimension lumber. Select Structural, #2 and better and stud grades are the most common. Specialty in-house grades and export grades are also available.
Appearance grades are also produced according to NLGA rules. Clears, shop lumber and moulding stock are most common, although there are many potential appearance grades that can be produced.
Douglas-fir lumber is dried according to end-use and customer specifications. Kiln drying inhibits natural staining of the wood, improves its strength and stiffness, enhances its appearance, and increases its resistance to decay and attack by insects.
Did you know?
Europeans discovered the superior qualities of B.C. timber for ship masts or spars in the late 1700s. British explorer Captain James Cook replaced a mast in B.C., likely with coastal Douglas-fir.
Photo credit: Michael Bednar
Get acquainted with the most commonly produced and exported lumber grades in boards and structural dimension lumber from B.C.’s interior softwood species.
Photo credit: Michael Bednar
| Density (kg/m3) | Green | 450 |
| Air dry | 487 | |
| Specific gravity (12% m.c.) | Standard | 0.45 |
| Hardness (N) | Side | 2990 |
| End | 4020 | |
| MOE (Mpa) | Green | 11100 |
| Air dry | 13500 | |
| MOR (Mpa) | Green | 52.0 |
| Air dry | 88.6 | |
| Compression parallel (Mpa) | Air dry | 50.1 |
| Compression perpendicular (Mpa) | Air dry | 6.01 |
| Shear (Mpa) | Air dry | 9.53 |
| Cleavage (N/mm width) | Air dry | 38.9 |
| Shrinkage OD = oven dry air = air dry 12% | Radial (OD) | 4.8% |
| Tangential (OD) | 7.4% | |
| Volumetric (OD) | 11.9% | |
| Volumetric (air) | 7.0% | |
| Tang / rad ratio | 1.5 |
| Colour | |
| Heartwood | Orange red to reddish-brown. |
| Sapwood | Yellowish-white (light in colour). |
| Heartwood / sapwood contrast | Sapwood is well defined and narrow in old-growth and up to 7 cm wide in second-growth. |
| Latewood / earlywood contrast | Pronounced difference in colour between earlywood and latewood zones. |
| Grain | |
| Wood is generally straight-grained, although there is sometimes a tendency for wavy or spiral grain to be present. | |
| Figure | |
| Plainsawn lumber or rotary-cut veneer: conspicuous growth ring pattern. | |
| Quartersawn lumber or quarter-sliced veneer: distinct, conspicuous latewood stripes. | |
| Knots | |
| Large knots with large areas of clear material in between. | |
| Other | |
| Wood is resinous, pitch pockets may be present. | |
| Process | Performance | Comments |
|---|---|---|
| Machining | ||
| Planing | Good planing quality | Good surface quality. Typical defects are raised grain and fuzzy grain. |
| Turning | High surface quality | Very good surface quality. |
| Sawing | Easy to work with tools | Easy to work with both hand and power tools. Moderate to severe blunting effect. Resin build up on cutters may cause problems. |
| Boring | Good | Very good boring quality. |
| Mortising | Excellent | Excellent mortising quality with both chain mortise and hollow chisel mortise. |
| Shaping | Excellent shaping quality | |
| Veneering | Excellent | Important plywood species. |
| Sanding | Good | Very good sanding properties. |
| Fastening | ||
| Screwing | Good | Very good holding. Excellent resistance to splitting. Average screw retention: 494 lb. |
| Lateral nail holding | Good | Good holding. Excellent resistance to splitting. |
| Nail retention | Good | |
| Gluing | Good to moderate | Bonds well with a fairly wide range of adhesives under a moderately wide range of bonding conditions. |
| Finishing | ||
| Staining | Easy | Old-growth: Smooth finish. Grain becomes wild and pronounced with dark stain. A clear coating works the best. Second-growth: Stainability is average for light colours, poor for dark ones. Good results with light stain or clear finish followed by nitrocellulose alkyd clear sealer and finish. Rotary cut veneers are reported to display such strong natural color that staining is sometimes unnecessary. |
| Painting | Average to good paint holding ability | Satisfactory to good results. |
| Lacquering | Excellent results | |
| Waxing | Good | Very good results are obtained when using light- to medium-coloured waxes, such as mellow pine and chestnut. |
| Drying | ||
| Ease of drying | Easy to moderately easy | A relatively easy wood to dry with little trouble occurring from checking, warping and splitting. Lower grades require more care. |
| Durability | ||
| Natural decay resistance | Moderately durable | Should not be used in applications with prolonged ground contact without treatment. |
| Treatability | Impermeable to extremely impermeable | Can be improved by incising. |
Data for these property tables has been compiled by FPInnovations from internal and external scientific sources.
FPInnovations is a not-for-profit technical research institute serving the Canadian forest sector.
