Building with wood is one of the oldest construction methods of all. Its physical and functional properties make wood an ideal material. If harvested in line with the speed of regrowth, the use of wood becomes very sustainable, especially where it involves short transport routes. But precisely the economically most important domestic European softwood species such as spruce or pine, have a weak point: They are not durable enough for many outdoor applications. In combination with moisture, they are susceptible to fungal attack. Affected wooden components lose their serviceability and have to be replaced. This is particularly important for structural timber.

Here, modern wood preservatives offer a solution. They are subject to strict European biocides legislation and are extensively tested and approved with regard to their effects on health and the environment. Their task: They increase the durability of wooden components in buildings and facades, in gardening and landscaping, but also in terraces, noise barriers, poles, railway sleepers and applications that are demanding in terms of safety or structure, such as children's playgrounds or wooden roller coasters.

Positive effects

The strongest argument in favour of wood preservatives is the significant extension of the service life of wooden components in weathered outdoor areas – by a factor of two to three. On the one hand, this means a significantly later release of the CO₂ stored in the wood and thus a valuable contribution to the goals of the revised LULUCF regulation (land use, land use change and forestry). On the other hand, less timber cutting is necessary as replacement for unfit wooden components.

Another aspect is the conservation of resources by avoiding the felling of more durable tropical wood. Making more domestic woods permanently usable reduces the need to import wood from highly climate-relevant tropical forests. The related transport costs and emissions are avoided additionally.

In figures

A comparative study from Scandinavia investigated the Global Warming Potential (GWP) on the example of decking made of different materials over a service life period of 30 years.

In addition to the reference material of a native softwood treated according to the NTR AB quality standard, the study also included other woods that do not require treatment (such as Siberian larch or the tropical wood Ipé) and further materials (e.g.wood-plastic composites / WPC from Germany and China) as well as concrete.  

The GWP of these different materials in the construction of a 30 m² terrace was examined and the respective GWP in CO₂ equivalents was determined – also including the respective transport routes. The result: Softwood treated according to NTR AB, with an expected durability of 30 years, was in the lead with 172 kg, followed by Ipé with 265 kg. Concrete and Siberian larch were close behind with 412 and 422 kg. The untreated Siberian larch was assumed to have a service life of only 15 years. The replacement of the wood in the period under consideration is directly reflected negatively in the GWP. The WPC products were far behind with 1296 kg (from Germany) and 1867 kg (from China).  

Conclusion

By way of example: When considering treated decking, domestic softwood proves to be a durable, sustainable, climate-friendly and economical alternative. This is where modern construction chemistry comes into its own!

The use of wood preservatives reduces the need to cut trees. Thus, forests are retained as CO₂-reservoirs and natural resources are effectively conserved.

Source

LCA on NTR treated wood decking and other decking materials, March 2018 (Danish Technological Institute Wood and Biomaterials/IVL Swedish Environmental Research Institute), ISBN 978-91-88787-37-8