Natural wood preservation: The ecological alternative
Natural wood preservation methods, i.e. the biocide-free killing of wood destroyers, meets the needs of many builders and owners for reasonable ecological and health control measures. The exclusive application of heat, which was awarded the „Blue Angel“ for good reason, meets all requirements for environmentally-friendly methods. In addition, chemical wood preservatives are classified as hazardous substances and, today, fewer and fewer people want to use them in areas that were previously so treated. Natural wood preservation offers a real alternative to this. However, in response to these really positive characteristics of natural wood preservation methods, we repeatedly encounter sceptical questions from customers who equate the word „eco“ with reduced efficacy or performance. The common stereotype is that heat treatment is not as effective as eliminating infestation through chemical means. However, in reality, the opposite is the case.
Biological wood preservation vs. chemical wood preservation
There are a large number of different means and methods for the elimination of wood-destroying insects and fungi. In addition to thermal, i.e. ecological wood preservation methods, a wide variety of chemical agents promise a remedy. However in many ways, the use of biocides is a disadvantage when compared with natural wood preservation. Thus, the chemical control of wood-destroying insects using so-called long-term means, are usually moult inhibitors. In this case, the larvae responsible for the destruction eat previously treated wood. The biocide taken in by the larvae thereby prevents the moulting process, which is vital for them. However, it may take weeks or months until this process is initiated and in the meantime the larvae live and eat unhindered. A guarantee of the success of the treatment can hardly be claimed in this way.
Controlling true dry rot in timber components with chemical agents is technically not possible. Only so-called sponge blocking agents are available for the treatment of contaminated masonry areas by preventing the growth and re-infestation of wood components. Upon completion of the chemical measure, there is still vital mycelium in the masonry. In addition, there are no reliable studies of the long-term effects of such agents.
The advantages of natural wood preservation
On the other hand, the destruction of wood-destroying insects and true dry rot through the natural wood preservation method is guaranteed – and it can be proven. Thus it is guaranteed that during the measurements performed during the heating, the necessary lethal temperatures are achieved and maintained. In addition, previously bred culture-grown infestation samples are inserted into the structure and then evaluated by the German Federal Institute for Materials Research (BAM – Bundesanstalt für Materialforschung). Their independent expert’s report gives again independent information on whether the biological wood preservation action was a success. However, ecological wood preservation has other advantages in the final destruction of the infestation. Thus, natural wood preservation methods also preserve value. While infested woods previously always had to be cut back in conventional wood preservation, since the penetration of chemical agents is limited to a few millimetres, heating can penetrate wood components to their core depending on the heating duration. While infested woods were previously classified as worth preserving, (almost) nothing stands in the way of remediation without dismantling.
New planning safety in ecological wood preservation
For a long time, only the thermal control of wood-destroying insects was normatively regulated, while the control of true dry rot existed as “special methods for individual cases”. Through scientific studies and follow-up of treated buildings, sufficient evidence was obtained that even true dry rot can be killed permanently. So the situation has fundamentally changed since 2012. Since then, the hot air method for thermal control of true dry rot has been regulated in DIN 68800, Part 4. This standard is the result of extensive studies on individual culturally historical monuments, but also for conventional housing, which clearly confirmed the effectiveness of ecological wood preservation. The reclassification as remediation-accompanying measures frees thermal wood preservation from its previous anonymity as the „special method for individual cases“ and provides building owners and architects with more planning options. In combination with its many advantages over wood preservation chemicals, it is to be expected that ecological wood preservation methods shall continue to spread in the coming years.