Since its creation in 1986, Tertu Equipements has always been convinced of the virtues of Douglas. Experience has shown that using this species produces high-quality, durable products with a low carbon footprint.
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An essence with a naturally sustainable heart
Over the years, Tertu has acquired in-depth knowledge of this species, enabling it to develop a wide range of products for road safety and site development.
Marketed in France and in more than 50 countries around the world, Tertu solutions have proven their effectiveness and longevity in a variety of environments and climates (temperate, tropical, dry, etc.).
A French resource
This species, also known as Oregon pine, originated in the United States and was introduced to Europe in 1827 by the British scientist David Douglas. It was introduced to France in 1842 as an ornamental tree.
After the war, this species was used to reforest France, which is why it can be found in several regions of France: Auvergne-Rhône-Alpes, Nouvelle Aquitaine, Bourgogne-Franche-Comté, Occitanie, Normandie, Bretagne, Centre, etc.
With around 420,000 ha, France has the largest Douglas fir forest in Europe.
Often criticised for its intensive use to the detriment of other species, Douglas has for several years been grown in irregular stands that favour biodiversity of species (coniferous/deciduous), generations of trees and stratification.
An essence with a big heart
The heartwood of Douglas fir, also known as heartwood, accounts for more than 80% of its composition; it has properties of natural durability and resistance to insects and fungi that are superior to those of most other European softwoods.
Untreated and sapwood-free, Douglas can meet the requirements of use classes 3.1 and 3.2.
‘A use class is not a performance class and does not give any indication of the service life of wood and wood-based products. (source Afnor)
The use class of wood is determined by standard NF EN 335 according to the risks of exposure to humidity.
There are 5 classes, each of which determines a degree of resistance, either through natural durability or durability conferred. The ‘natural durability’ of a wood only concerns the heartwood.
Natural durability: Intrinsic capacity of a species (excluding sapwood) to resist wood deterioration agents (lignivorous fungi, xylophagous larvae, etc.).
The durability of a wood against the risk of fungi is the combined factor of two fundamental parameters: natural durability and impregnability.
Natural durability (as defined in NF EN 350) is essentially determined by laboratory tests, the protocols for which are based on creating ideal conditions for fungal development (humidification + inoculation with fungal strains).
“In use, the impregnability factor has a major impact, especially in use class 3. For equivalent natural durability, a species that is highly resistant to water absorption will last longer in the structure than a species with average or even high impregnability. Douglas fir, for example, is a perfect example of this”. (Extract from the AFNOR documentation booklet)
Exceptional technical and mechanical properties
Thanks to its excellent mechanical and structural properties, Douglas fir is a preferred choice for projects requiring particularly high strength. Tertu is convinced of these qualities and has always used this species in the design of its solutions.
Over the years, Tertu has perfected its expertise in the use of Douglas fir, even going so far as to introduce the innovative ‘Essentiel’ concept to the market. This concept is based on the exclusive use of untreated, naturally durable Douglas fir heartwood in the design of its solutions. By adopting this approach, Tertu seeks to maximise the intrinsic benefits of this species while minimising its impact on the environment and offering products that respect sustainability.