Wood preservatives

from Wikipedia, the free encyclopedia
Telegraph pole partially decomposed by fungi, cross-section near the ground.

Wood preservatives are active ingredients or preparations containing active ingredients which are intended to prevent or to combat such an attack on wood or wood-based materials by organisms that destroy or discolour wood . See: wood protection

Coating materials such as paints or inks that do not use drugs against wood-destroying or - discoloring are equipped organisms or exclusively active ingredients for self-protection of the coating contain do not fall under the term "wood preservatives", although they are quite used to the protective treatment of wood. Likewise, the means to protect the wood from graying through the sun's UV radiation , the so-called weather protection agents, and the means to protect the wooden surface from stains , dirt and dust with a decorative effect, the so-called wood finishing agents , are not assigned to the wood preservatives. In addition to the use of wood preservatives, a number of other wood preservation processes with preventive or combating effects are also used.

In Germany , sales in 2014 with wood preservatives and varnishes in paint quality were 135 million euros.

The European Directive 98/8 / EC of February 16, 1998 on the placing on the market of biocidal products defines wood preservatives as products to protect wood from the cut in the sawmill , or wood products against attack by organisms that destroy wood or impair wood quality . This type of product includes both preventive and curative products .


Legal regulations

Damage to the shipworm

As a mixture of different chemical substances and compounds, wood preservatives are subject to the applicable statutory regulations such as chemicals , environmental and waste laws . In particular, as biocidal products, they fall under the scope of the biocidal legislation . The basis for this is Regulation (EU) No. 528/2012 (Biocide Regulation) . It regulates the sale, supply (making available on the market) and use of biocidal products throughout Europe. The Biocide Ordinance therefore affects both dealers, distributors and users of biocidal products, which in turn is part of the Chemicals Act . According to the Biocidal Products Ordinance, wood preservatives fall under product type 8 (products to protect wood, from the cutting in the sawmill, or wood products against attack by organisms that destroy wood or affect the quality of the wood, including insects. This type of product includes both preventive products and curative products.) The biocide legislation requires that the active substance to be used is first approved at EU level, then approval must be given by an approval body for biocidal products to be marketable. The prerequisite for this is a health and environmental assessment as well as proof of effectiveness. The wood preservatives approved in Germany can be accessed online via the database of the Federal Institute for Occupational Safety and Health .

Regulations for the use of wood preservatives in buildings

In Germany, DIN 68 800 wood protection defines the application of measures that prevent the deterioration or destruction of wood and wood-based materials - especially by fungi, insects, etc. Furthermore, builders must observe the BGB and its duty to maintain safety in order to protect third parties. In the interest of public safety , the legislature prescribes preventive protection of timber used for load-bearing or stiffening purposes. Violations are prosecuted as an administrative offense. If, in the event of damage injured persons can possibly criminally punishable. If a builder insists on the use of unimpregnated timber, architects and builders can exclude the builder's claim for damages under civil law . However, this is not effective against third parties and such clauses are irrelevant under public law and criminal law. The wood can also be protected by constructive measures , such as the use of insect and / or rot-resistant types of wood or an environment that is as dry as possible ( moisture content of the solid wood below 20%).

Building supervision certificate of usability

A building supervisory usability certificate in the form of a general building supervisory approval according to the building regulations of the federal states is required

  • Preparations for the preventive protection of building products and components made of wood for load-bearing and / or stiffening purposes against wood-destroying fungi and insects,
  • Means for the preventive protection of building products and components made of wood-based materials against wood-destroying fungi and insects,
  • Means to combat an existing infestation of components made of wood and wood-based materials by wood-destroying insects,
  • Means for preventing the through growth of masonry by the dry rot (sponge blocking means).

The general building inspectorate approval, which is valid in all federal states , is issued by the responsible German Institute for Building Technology (DIBt). The DIBt publishes an annual list of wood preservatives in which the approved wood preservatives are listed. The period of validity of the authorization is limited (maximum 5 years).

The issuing of the building authority approval is primarily dependent on evidence that the wood preservative is suitable for the intended purpose and effective when used as intended. Furthermore, within the scope of the approval, not only the direct handling of the wood preservative is assessed with regard to possible effects on health and the environment, but also the treated wood during the use phase.

The effectiveness test takes over z. B. the Federal Institute for Materials Research and Testing (BAM).

Depending on their effectiveness and their later intended use ( use class ), the funds receive the following test ratings:

  • Iv: effective preventive against insects
  • P: effective preventive against fungi ( rot protection )
  • W: also for wood that is exposed to constant weather , but not in constant contact with the earth and not in constant contact with water
  • E: also for wood that is exposed to extreme stress (in constant contact with the ground and / or in constant contact with water as well as dirt deposits in cracks and joints )
  • Ib: effective against insects
  • M: to prevent dry rot from growing through masonry

Wood preservatives with a general building inspectorate approval may only be used by specialists or specialist companies with experience in wood preservation.

No building authority certificate of usability is required, however

  • Agents for the preventive protection of building products and components made of wood for non-load-bearing and non-stiffening purposes (e.g. for external wall or sub- formwork , windows , external doors , shutters ),
  • Means for the preventive protection of objects that are not part of a structure within the meaning of the state building regulations (e.g. garden furniture, benches, fruit stakes),
  • Means for combating an infestation by wood-destroying insects of objects that are not part of a building structure within the meaning of the state building regulations (e.g. old furniture),
  • Agent for the preventive protection of wood outdoors without contact with the ground, including windows and external doors, against organisms that discolour wood.

For these wood preservatives, which are not regulated by the building authorities, there is the option of having their effectiveness and their health and environmental effects officially tested and assessed on a voluntary basis, e.g. B. according to RAL-GZ 830 of the Gütegemeinschaft Holzschutzmittel e. V. None of these agents are intended for use in living rooms and lounges.

Instructions for use

Standards (selection)

  • DIN 68800 wood protection in building construction
    • Part 1 - General (Edition 2011-10)
    • Part 2 - Preventive structural measures in building construction (Edition 2012-2)
    • Part 3 - Preventive protection of wood with wood preservatives (Edition 2012-2)
    • Part 4 - Control and remedial measures against wood-destroying fungi and insects (Edition 2012-2)

Wood protection products

Wood preservatives

Wood treated with brown carbolineum . The agent penetrated almost to the center of the post. Only later was it cut into its semicircular shape

Wood preservative can be classified according to their composition, their application purpose and procedures (for preventive protection or to combat an existing infestation or processing by means of specific application techniques such as printing method , Trogtränkung , brushing ), its effectiveness ( fungicidally , insecticidally , bläuewidrig ) or commercial forms ( aqueous ready-to-use agents, water-dilutable salt concentrates or emulsions , solvent-based ready -to- use agents). A special role Preparations based on coal tar oil (Carbolineum), which only means of specific methods and only in specified areas of application (such as utility poles , iron sleepers , Reb - and fruit piles ) may be used.

The 2009 list of wood preservatives makes the following classification for wood preservatives with general building authority approval:

Preventive wood preservatives:

Water-soluble wood preservatives for the preventive protection of wooden components against wood-destroying fungi and insects (main components or active ingredients):

  • Boron - salts ( inorganic boron compounds)
  • CK salts (inorganic chromium - copper compounds )
  • CKB salts (inorganic chromium, copper and boron compounds)
  • Quat preparations ( quaternary ammonium compounds )
  • Quat boron preparations (quaternary ammonium boron compounds)
  • Chromium-free copper preparations (copper compounds, Cu-HDO or quaternary ammonium compounds , e.g. with the addition of triazole derivatives and / or boron compounds)
  • Collective group (preparations that differ in their composition from the aforementioned active ingredient combinations or whose effectiveness is based on other substances)

Solvent-based wood preservatives for the preventive protection of wooden components against wood-destroying fungi and insects:

Wood preservative for the preventive protection of wooden components against wood-destroying insects - without any effectiveness against wood-destroying fungi:

Wood preservatives exclusively for the preventive protection of wood-based materials against wood-destroying fungi - without any effectiveness against wood-destroying insects:

  • Special preparations for wood-based materials (inorganic boron compounds, potassium HDO)

Combating wood preservatives:

Wood preservatives with combating effectiveness against wood-destroying insects:

  • Control agents (ready -to -use solvent - based preparations, water-soluble salt concentrates and water-thinnable emulsion concentrates )

Means of using dry rot throughgrowth through masonry:

  • Sponge barrier agent (boron compounds, quat and quat boron compounds)

Only those active ingredients may be used in wood preservatives that have either been assessed in accordance with European Directive 98/8 / EC of February 16, 1998 (inclusion in Appendix I or IA) or are still in the review program for existing active ingredients ("review program"). Lindane (HCH), DDT , pentachlorophenol (PCP) and mercury compounds are no longer permitted . DDT and PCP, in particular, are still found in the woods decades after treatment due to their low vapor pressures . Even today, these no longer permitted wood preservatives in existing buildings represent building pollutants that are more common and often lead to costly pollution remediation.

Products with a physical protective effect, without the addition of active ingredients

A wide range of different products aim to prevent moisture build-up in the wood and to protect the wood surface from mechanical ( wind , driving rain , dirt) and physical effects (UV radiation from the sun). These do not count as wood preservatives in the narrower sense, as they do not contain any active ingredients that are directly directed against wood pests. Are used impregnations as hydrophobizing agent (often in different colors) and means for surface treatment of wood.

Some of these agents are offered as "biological wood preservatives". This term is neither defined nor protected. According to their manufacturers, these agents do not require any artificial biocides ( insecticides and fungicides ). The effectiveness of these agents is limited to a preventive effect. According to the manufacturer, these products work by covering up the wood-specific, odor-intensive aerosols so that they are no longer perceived by wood-damaging insects.

Other agents fill the pores and modify the wood surface so that a wood-damaging insect cannot recognize the surfaces treated with such an agent as wood. However, sustainable prevention of egg laying can all then only through a complete treatment anfliegbaren succeed wood surfaces (this is also true when treated with wood preservatives). So far, no general building inspection approval has been granted by the DIBt for any of these preparations, as the effectiveness of the agents has not been proven.

Glazes and varnishes

Glazes and varnishes are film-forming . They therefore mostly stay on the surface and do not penetrate the wood. Glazes usually let the wood surface shine through. Thick-layer glazes achieve application thicknesses like paints. Thin-layer glazes are mainly used for non-dimensionally stable components such as cladding , fences or pergolas . They delay the wood from entering a moisture equilibrium with the ambient moisture , but do not prevent it. The thin glaze film is open to diffusion and can in some cases be treated afterwards with little effort. Thick-layer glazes are usually used for dimensionally stable components such as windows and doors . They reduce the moisture absorption of the wood and thereby largely prevent the wood from swelling or shrinking.

Paints and glazes as weather protection agents are formulated on a solvent basis as well as on a water basis . Protection against lignin- degrading UV light is achieved by adding pigments or special UV filters . Weather protection agents are often added to film or in-can preservatives in order, in particular in the case of water-based agents, to prevent fungal attack on the paint film or on the agent itself. The Federal Environment Agency has set ecotoxicological criteria and upper limits for the content of drip and film preservatives for weather protection agents that bear the environmental label: Eco-label because they are low in pollutants according to RAL -UZ 12a . Unlike wood preservatives, however, these agents are not subjected to any ecotoxicological assessment by the Federal Environment Agency.


Oils or waxes primarily protect the wood surface from physical damage, such as moisture absorption , stains and, in the case of hard oils, scratches . Since the pores are closed, the surface can be cleaned more easily. Pigmented or specially treated oils also protect against UV rays. When waxing, the protection is only superficial. Since they weather easily and are infiltrated by moisture, they are only suitable for use on indoor surfaces that are not exposed to moisture frequently and for long periods of time.

Silicification and silylation

Water glass has been used as a fire retardant since the 19th century and at the same time has certain wood-preserving functions. After the application, it can take years for the paint to set ( silicified ) completely . In the weathered outdoor area, the water glass would therefore be washed out of the wood again.

Water glass is absorbed very deeply into the wood. Since it is an aqueous solution, it can cause the wood to swell temporarily. Most types of wood darken a little when water glass is applied. Young oak takes on the color of old. Light woods such as ash and hornbeam are good for treatment.

Potash and lithium waterglass are more stable than soda waterglass.

After 1942, many roof trusses were soaked in water glass to protect them from the fire. This treatment often left a whitish coating and the wood was largely spared from insect infestation.

In addition to water glass, other silicon compounds such as silica sols and alkyl and alkoxy silkanes are used for silicification or silylation . All these processes lead to a weight increase of 20 to 50%, depending on whether the wood has been impregnated on the surface or treated with pressure impregnation . They are also counted among the methods of wood modification .

The Frankfurt Wood Preservation Process 1991 to 93

In the so-called “ Frankfurt Wood Preservation Trial ”, the Greater Frankfurt Regional Court sentenced the two managing directors of the wood preservative producer Desowag to one year probation and a fine of DM 120,000 for negligent bodily harm and the release of poisons. It was about wood preservatives, which had contained the highly dangerous active ingredients pentachlorophenol (PCP) with impurities of dioxin and lindane and which had been applied millions of times to wooden components such as roof trusses and wall paneling by the early 1980s. The Federal Court of Justice overturned the regional court's judgment due to two formal errors. In the SWR television documentary by Mirko Tomic, the then prosecutor, public prosecutor Dr. Erich Schöndorf that he had been put under great pressure at the time to stop the proceedings and that today the same problem continues to exist in a similar form.


  • Wood protection regulations on dhbv.de.
  • DIN 68800, parts 1–5. Beuth-Verlag, Berlin.
  • DIN , DGfH (Ed.): Wood protection. Structurally - chemically - fighting. Explanations to DIN 68800 part 2, -3, -4. Beuth Verlag, Berlin 1998, ISBN 3-410-13959-1 .
  • German Institute for Building Technology (DIBt) (Hrsg.): Directory of wood preservatives. List of wood preservatives with general building authority approval - List of wood preservatives with RAL quality mark - List of blue stain protection agents in accordance with VdL guidelines. 57th edition. Status: April 2009, Erich Schmidt Verlag, Berlin, ISBN 978-3-503-11639-3 .
  • ARGE Holzschutzmittel (Hrsg.): Österreichisches Holzschutzmittelverzeichnis 2010. 42nd edition. 2010. (Download as pdf) .
  • Johann Müller: Wood protection in building construction. Fraunhofer IRB Verlag, Stuttgart 2005, ISBN 3-8167-6647-1 .
  • Dietger Grosser: Plant and animal construction and timber pests. DRW-Verlag, Leinfelden-Echterdingen 1985, ISBN 3-87181-312-5 .
  • Hans-Peter Sutter: Recognizing and combating wood pests on cultural assets. Verlag Paul Haupt, Bern / Stuttgart / Vienna 2002, ISBN 3-258-06443-1 .
  • G. Becker: Studies on the nutritional physiology of the longhorn beetle larvae. In: Journal of Comparative Physiology . 29/3, 1942, pp. 315-388.
  • W. Behrenz, G. Technau: Investigations on the immunization of wood by hot air treatment . In: Wood as raw and material (European Journal of Wood and Wood Products), Volume 14, Issue 12, 1956, pp. 457–458. doi: 10.1007 / BF02605506 .
  • Uwe Wild: Lexicon of wood protection. BAULINO Verlag, Waldshut 2009, ISBN 978-3-938537-07-7 .
  • P. Weissenfeld, H. König: wood protection without poison. Ökobuchverlag, Staufen 2001, ISBN 3-922964-12-5 .

Web links

Individual evidence

  1. Sales of paints and varnishes declining, DIY store manager, July 20, 2015
  2. a b Official Journal of the European Communities: DIRECTIVE 98/8 / EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of February 16, 1998 on the placing of biocidal products on the market (PDF; 432 kB).
  3. Information from the construction trade association on the use of wood preservatives ( memento from September 23, 2015 in the Internet Archive ), accessed online on August 26, 2015.
  4. Internet address of the Gütegemeinschaft Holzschutzmittel e. V. with information on RAL-GZ 830 .
  5. Information from the EU regarding Directive 98/8 / EC ( Memento of December 5, 2006 in the Internet Archive ).
  6. a b c Expert office for wood protection Hans-Joachim Rüpke and Dr. Ernst Kürsten: [www.holzfragen.de/seiten/modifikation.html#5 Wood protection through wood modification - silicification / silylation]; In: Holzfragen.de
  7. LC Marquart: [dingler.culture.hu-berlin.de/article/pj140/ar140102 CII. Instructions for using the water glass; by Dr. LC Marquart in Bonn.], 1856; In: Dingler.Culture.HU-Berlin.de
  8. Test: Holzschutzmittel Published on: October 7, 1996
  9. " The wood preservative victims - legally poisoned, then forgotten "