Technical commission 1 – Timber – handles the following matters:

  • Biotic and abiotic damaging effects
  • Timber preservation in building construction, selection of timber, structural timber preservation, chemical timber preservation, weather protection
  • Remedial timber preservation
  • Waste timber
  • Decontamination of polluted timber
  • Repair work, completion of missing timber sections, timber repair, structural upgrading of timber
  • Coatings, processing and coating of lead contaminated timber


This technical commission participates in the expert discussion of subjects such as timber in general, timber-based materials, structural timber preservation, preventive and remedial timber preservation, use of waste timber, completion of missing timber sections, repair and upgrading as well as standardization projects. The competencies of the members of this technical commission are bundled through the compilation of WTA codes of practice covering the abovementioned subjects. If necessary, the latest topics are promptly handled by the existing or ad hoc working groups. Other objectives of this technical commission are the transfer and sharing of knowledge. Technical commission 1 addresses all interested circles of experts on the subject of timber and timber preservation and thus bundles technical competencies in this area. This technical commission is the symbiosis between science and practice in the construction industry.


Dipl.-Ing. Gero Hebeisen

Dipl.-Ing. Ekkehard Flohr
Ingenieurbüro Ekkehard Flohr GmbH

Lutz Parisek
Parisek saniert GmbH + Co.KG

Dr. André Peylo

Number of members: 88


Technical commission 1 will continue to deal with the topics of timber, derived timber products and timber preservation in the building construction and will take up and deal with all related topics. The technical commission will continue to pursue its goal of knowledge transfer for practice and will combine the technical competence in the unit and in the working groups and make the knowledge summarized in fact sheets available to the professional world and practice for application.

Future topics

  • Modified woods
  • Timber constructions, extensions, finishing
  • Use of thermowood
  • Energy, resource management, planting and harvesting
  • Built-in and freely weathered timber
  • Infrastructure structures
  • Building physics topics through use and application
  • Fire protection measures and requirements
  • Digitization Wood 4.0

26.01.2023 Working group "Decontamination" reactivated

Under the leadership of Dipl.-Ing. Thomas Löther und Dipl.-Ing. (FH) Erich Jelen , working group 1.9 "Decontamination" was reactivated.

The task of the group is to revise the guidelines 1-8 "Decontamination of wood contaminated with wood preservatives I: Identification and risk assessment" and 1-9 "Decontamination of wood contaminated with wood preservatives II: Depletion of wood" from 2013.

The next working group meeting is planned for the end of March in Fulda.

If you are interested in participating in this working group, please contact the office or the working group leaders directly.

27.04.2021 New Working Group 1.18 "Fumigation and Modified Atmospheres for the Control of Animal Wood-Destroying Organisms in Structures"

The use of toxic fumigants and modified atmospheres has long been anchored in the wood preservation standard DIN 68800-T4. In the area of the WTA, the topic of fumigation has so far only been mentioned to a very limited extent in the guidelines 1-10 Special Methods in Wood Preservation Part 1: Control Methods.

Compared to fumigation, the guidelines 1-1 Hot Air have long been regarded as a proven WTA guideline in the field of control methods.

The aim of the guidelines is to provide comprehensive information on the use of fumigants in heritage conservation, including current possibilities and limitations. Similar to other guidelines, possible target organisms (e.g. animal wood pests), currently used fumigants, historical materials worthy of protection (wood, paper, books, textiles), definitions of terms, technical requirements and process control are to be addressed.

The start of the work is planned with the foundation meeting (if Corona conditionally possible) in Fulda on Tuesday, 20.07.2021.

Should you be interested in participating in this working group, please contact the office or the initiator of the working group Mr. Dipl.-Ing. (FH) Stephan Biebl.

24.03.2021 New Working Group "Timber Bearings"

The new working group in technical commission 1 wants to deal with the problems of contact between wood and other building materials in structures.

Timber components that rest on other building materials can be endangered by moisture conduction. This is particularly the case with mineral building materials (e.g. masonry).
The settlement of wood-destroying organisms (fungi and insects) due to an increased moisture load on the supported wood is to be examined. The causes of the damage, the organisms, their control and the constructional-technical strengthening of the building components are to be explained.

Possible components are: Beam heads, sills, wall battens, timbers in eaves areas, underlay timbers, jamb stiles, column bases, wall cladding, lambris, etc.

New regulations (DIN 68800/2) and existing WTA guidelines (8-14, 1-8, Bautechnischer Holzschutz) are taken into account.

The working group  1.10 "Timber Bearings" (currently the working title) is expected to hold its first meeting in autumn.

Initiator of the working group is Mr. Ekkehard Flohr.

If you are interested in participating, please contact the office or directly the initiator of the working group Mr. Flohr.

We look forward to your feedback! 

10.03.2021 New Working Group "Timber Anatomy"

Timber is a fascinating building material. As a natural material, however, it has variable properties even within a trunk. On the other hand, there is an increasing belief in regulations that try to standardise this building material in terms of durability, serviceability, use class, etc.

An essential characteristic of some types of wood is the natural durability of the heartwood against environmental hazards from fungi and insects. Sapwood is never durable. However, anatomical peculiarities that lead to low water absorption also influence the durability of a component. Non-durable spruce can therefore, under certain circumstances, last longer as a window frame, for example, than a truss made of durable oak.  
In addition, reactions in the living tree, e.g. to injuries, influence the subsequent wood properties. In the practice of trade and processing, these complex interrelationships are often disregarded or even unknown.

For this reason, the working group "Timber Anatomy" (better "Durability") was founded. The aim is to present the diversity of wood properties, to show practical application possibilities and their limits on the basis of influencing parameters (moisture, time).
At the same time, new findings, e.g. on the durability of oak reaction wood, are to be collected.

If you are interested in participating, please contact the office or directly the initiator of the working group, Dr. André Peylo.

We look forward to your feedback!

Working Groups

The following working groups are or have been concerned with the work on recommendations.

Current working groups

Working group 1.1:

Dry rot

Working group 1.2:

Structural timber preservation

Working group 1.3:

Hot air processes for control wood pests

Working group 1.4:

Sampling and diagnostics

Working group 1.5:

Waste timber

Working group 1.6:

Coating of timber in existing structures

Working group 1.7:

Completion of missing timber sections

Working group 1.8:

Special procedures in timber preservation

Working group 1.9:


Working group 1.10:

Supported timber

Working group 1.11:

Mould on timber

Working group 1.12:

Reed-thatched roofs

Working group 1.14

Timber Anatomy

Working group 1.18


New working groups are planned to deal with the following topics.

Planned working groups

Timber preservation in a Europe-wide comparison

History of timber processing


Wood pests

Anatomy of timber




The following recommendations have been published by the Technical Commission "Timber and Timber Protection" :

1-1    Edition: 06.2008/D

Thermal processings for control of insects attack on wood in buildings

1-2    Edition: 03.2005/D

Dry rot – identification, living conditions, preventive measures, controlling chemical measures, list of performance

1-4    Edition: 12.2000/D

Construction protection of wood on historical buildings – Part 2: Roof truss

1-6    Edition: 10.2013/D

Sample taking on Wood – Research on fungi, insects, wood preservatives, wood age and wood type

1-7    Edition: 09.2012/D

Wood supplement

1-8    Edition: 11.2013/D

Disinfection of  timber, contaminated by wood protection compounds, Part 1: Assessment and Risk evaluation

1-9    Edition:11.2013/D

Disinfection of timber, contaminated by wood protection compounds, Part 2: Procedures for reduction of contamination

1-10  Edition: 09.2015/D

Special measures to control and prevention of wood-destroying insects and fungi in wooden material


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