Douglas Fir

Douglas Fir

Pseudotsuga menziesii
Other name: Oregon pine

General description

The country of origin of the Douglas fir is the North West of America. It was introduced 200 years ago in Europe. Properties of the European Douglas Fir (most with a rapid growth) are different from those of its area of origin.

Wood description

The heartwood with its pinkish to dark red colour is clearly demarcated from the yellow sapwood, which has a thickness between 5 and 10 cm. The texture is medium, the timber has a straigght grain.
Douglas Fir may show some resin pockets, sometimes of great dimensions. Softwoods have medium density and good strength properties.
Gluing and sawing properties are good, but due to resin pockets of saw blades may occur. Nailing and screwing properties are good, but pre-boring is necessary and there is a strong tendency to split.

Common uses

The uses of Douglas Fir are similar to those of Larch, mainly for building and construction.

Physical characteristics
Density (at 12 % moisture content) 540 kg⁄m3
Total longitudinal shrinkage 0.3 %
Total radial shrinkage 4.5 %
Total tangential shrinkage 7.5 %
Equilibrium moisture content  
(20° C⁄ 37 % rel. humidity) 8.3 %
(20° C⁄ 83 % rel. humidity) 16.1 %
Mechanical characteristics
Modulus of elasticity under bending 12500 N⁄mm2
Modulus of rupture under bending 95 N⁄mm2
Tension strength 100 N⁄mm2
Compression strength 50 N⁄mm2
Brinell hardness perpendicular to the fibres 20 N⁄mm2
Janka Hardness 2,5 kN
Nail withdrawal strength in N per mm depth and mm diameter 9.0 N⁄mm2
Natural durability and treatability (according to en 350-2)
Fungi Class 3 – 4 moderately to poorly durable
Dry wood borers durable
Termites Class S susceptible
Treatability 4 – not permeable

Natural durability is based on mature heartwood. Sapwood must always be considered as non durable against wood destroying agents.