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Douglas-fir
Short Description
Coniferous wood
Description
The Douglas fir is originally native to western North America, growing at higher altitudes along the Pacific coast of British Columbia to California and inland from Alberta to North Mexico. There are considerable quantities in Oregon which accounts for the popular American name "Oregon fir". Douglas fir is the most widely used wood for building and construction.
In 1828 seeds were brought to Europe by the Scottish researcher David Douglas. Up until the Ice Age a related sort was widespread throughout Europe, but only the American relative survived. The Douglas fir has been planted in Germany and throughout Europe since around 1880.
Up until the end of the 19th Century its relation to other conifers was unclear. A number of different names added to the confusion: Douglas fir, Douglas pine and Douglas spruce. Although still commonly known as Douglas fir it belongs to its own botanical family "Pseudotsuga" (false hemlock).
The Douglas fir is differentiated in different variants, whereby the green coast Douglas fir is the most important in Europe. They belong to some of the highest growing trees in the world. In their native environment they can grow to between 50 and 75m high, some occasionally as high as 90m.
The sapwood and heartwood are quite different in colour: the sapwood in yellowish to reddish-white, fresh heartwood yellowish-brown to reddish-yellow in colour and darkens quickly to a brown-red to dark-red colour. The darker colouring often has a similar appearance to larch.
The tree grows quickly for the first 50-60 years which can be seen in the annual growth rings of the heartwood which are initially broader, growing gradually thinner. Imported wood from America often has a finer ring pattern. Depending upon the location and growing conditions of the trees, the properties of the wood can vary considerably. Fine annual growth rings, few branches and low sap content are indicators for good properties.
Properties
The wood of the Douglas fir is medium-weight and, in comparison to other coniferous woods, fairly hard. It is subject to low shrinkage and has good stability. It is strong and elastic.
The wood is also resistant against fungal and insect infestation and exhibits good natural durability when exposed to the elements.
Usage
Fine ring patterned wood is softer and easier to work than broad-ring wood. For outdoor use, iron-free metal is recommended for constructive connections in order to avoid colouring of the wood. Surface finishing should take into account the fairly high sap content of the wood, either through the choice of a suitable paint or by sorting out the high sap content timber.
Dimensions
Native Douglas fir is available as round and sawn timber.
In the USA, Douglas fir is known as "red fir" (reddish, broad annual growth rings) or yellow fir (yellowish, fine annual growth rings).
Applications
- Building and construction
- Balconies, Pergolas
- Parquet flooring, stairs, flooring
- Façade and wall panelling
- Hydraulic engineering
- Production of cellulose products, fibrous panelling, plywood
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