Spruce Wood Uses and Propertiess
The three softwoods comprising the principal species in the spruce-pine-fir (SPF) species group share many common characteristics and properties, as well as the same native habitat in the montane, boreal and subalpine forest regions of British Columbia (B.C.) and Alberta. White spruce, Lodgepole pine and Alpine fir are all trees of medium size, averaging 30 metres in height and up to 80 centimetres in diameter. They are hardy trees, relatively slow-growing and yield high-grade timber with small, sound, tight knots. Well suited to the cold winters and hot summers that characterize the continental climate of their northern forest area, trees of the SPF group are the most abundant softwoods in Canada and the most commercially important. Forest reserves are estimated at more than 500 million cubic metres, and reforestation efforts already in place assure excellent continuity of supply over the long term.
Common exterior uses
Spruce-pine-fir's strength, light weight, ease of handling and good working properties have made it a popular wood for framing applications in all types of construction. Strong, stiff and stable, SPF is well-known and highly regarded not only in North America, but also in Europe and Japan. Readily available in a wide range of sizes and lengths, including finger jointed lengths up to 12 metres, it is an extremely versatile lumber for residential, commercial, industrial and agricultural buildings. SPF is a particular favourite with house builders, who appreciate its high structural performance as well as its pine appearance.
The prefabrication industry is also a major user of SPF because of the wood's strength, dimensional stability and superior gluing properties. Manufacturers of modular houses, trusses and other structural components, regularly specify kiln-dried SPF as a wood they can rely on for consistent quality and ready availability in precise dimensions.
Appearances and properties
In contrast with other commercial softwoods, SPF is a distinctly white wood, with very little colour variation between springwood and summerwood. The wood has a bright, clean appearance, ranging in colour from white to pale yellow, with a pine straight grain and smooth texture. SPF has a high strength to weight ratio and is well known for its outstanding working properties. It takes and holds nails exceptionally well and is easily worked with hand power tools. It has good gluing, painting and staining properties. Lumber of this species group is seasoned uniformly in dry kilns to a moisture content of 19 percent or less. Kiln drying inhibits natural staining of the wood, improves its strength and stiffness, enhances its appearance, and also increases its resistance to decay and attack by insects. The drying process also improves the wood's dimensional stability, finishing qualities and thermal resistance while at the same time reducing shrinkage, warping and checking in storage.
Physical properties
|
|
Spruce |
Pine |
Fir |
| Stiffness / MOE (MPa) |
Air dry |
10000 |
10900 |
10200 |
| Strength / MOR (MPa) |
Air dry |
63 |
76 |
56 |
| Density (KG/M3) |
Air dry |
380 |
430 |
351 |
| Compression Parallel (Mpa) |
Air dry |
36.9 |
43.2 |
35.4 |
| Shear (Mpa) |
Air dry |
6.79 |
8.54 |
6.74 |
| Shrinkage (air dried-12%) |
Tangential/radial ratio |
2.2 |
1.4 |
2.8 |
| Working Properties |
Title |
Process |
Performance |
Comments |
| White Spruce |
Machining |
Planing |
Very good |
Good planing quality; recommended planer settings: 12° or 20° hook angle and 20 kmpi (knife marks per inch) |
|
|
Shaping |
Good |
Good shaping quality |
|
|
Sanding |
Very good |
|
|
Fastening |
Screwing |
Good |
Very good resistance to splitting |
|
|
Nail retention |
Good |
Very good resistance to splitting |
|
|
Gluing |
Average |
|
|
Finishing |
Staining |
Good |
Good staining properties, a smooth finish is achieved; a natural finish (clear coat) or a light stain looks the best |
|
|
Painting |
Average |
|
|
Drying |
Ease of drying |
Good |
Spruce dries faster than pine and is not adversely affected by severe high-temperature schedules |
|
Durablity |
Natural decay resistance |
Poor |
Not appropriate for prolonged outdoor exposure |
|
|
Treatability |
Fair |
Can be improved by incising |
| Lodgepole pine |
Machining |
Planing |
Excellent |
Recommended planer settings: 20° hook angle and 8, 12, or 16 kmpi (knife marks per inch) |
|
|
Shaping |
Good |
|
|
|
Sanding |
Good |
|
|
Fastening |
Screwing |
Average |
|
|
|
Nail retention |
Average |
|
|
|
Gluing |
Easy |
|
|
Drying |
Ease of drying |
Good |
Few defects expected except in the most extreme cases |
|
Durablity |
Natural decay resistance |
Poor |
Not appropriate for prolonged outdoor exposure |
|
|
Treatability |
Fair |
Can be improved by incising |
| Alpine Fir |
Machining |
Planing |
Good |
Recommended planer settings: 20° hook angle and 8, 12, or 16 kmpi (knife marks per inch) |
|
|
Sawing |
Good |
|
|
|
Shaping |
Good |
|
|
|
Sanding |
Good |
|
|
Fastening |
Screwing |
Average |
|
|
|
Nail retention |
Average |
|
|
|
Gluing |
Easy |
Bonds very easily with adhesives of a wide range of properties and under a wide range of bonding conditions |
|
|
Staining |
Easy |
Smooth finish with little texture, dark stain can highlight prominent wild grain; recommended: light-coloured stains with low penetration power will produce a more even colour |
|
Finishing |
Painting |
Average to good |
|
|
Drying |
Ease of drying |
Good |
Few defects expected except in the most extreme cases |
|
Durablity |
Natural decay resistance |
Fair |
Not appropriate for prolonged outdoor exposure |
|
|
Treatability |
Poor |
Can be improved by incising |
