WoodExter – Service life and performance of exterior wood above ground

Project Objectives
The main objective of WoodExter is to take the first steps towards introducing performance-based engineering design in practice for wood-based building components in outdoor above ground situations.

Project Approach
Three sub-projects will provide input for the development of an engineering type model for the prediction of service life of wooden constructions above ground:
-how different climates and end-use situations will affect the performance of wood
-the role of surface coatings interacting with wood
-development of indicators to produce in-service performance predictions with respect to the progress of decay. Additionally, there will be sub-projects for knowledge transfer and management.

Expected Project Impact
By using data on biological degradation of different wood-based materials and the role of use conditions, climate and designs, the project is expected to result in a model for estimation of service life of wooden constructions. Focus will be on cladding and decking. For further development and demonstration of the usefulness of the model a number of demonstration objects will be established. The most important issue for industry is that the project will provide a strong steer for future standardisation work within CEN, but also the input to the design of buildings.

100 years’ service life of wood in service class 1 and 2 – dry and moderately humid condition.

The service life of structures is an important part of the life cycle planning of buildings and structures. It has also an essential effect on the carbon footprint of the building, since this determines the length of the use phase of the building or a building part.

Material performance based models to estimate the service life of building materials and structures has been used for the service class 1 or 2 conditions (dry or moderately humidity conditions). There is more research done for the service class 3 and 4 conditions, where the exposure conditions are much harder. Potential factor method is shown in the ISO 15686 series on service life evaluation. The best way to estimate the service life of timber structures is based on existing experience, which can then be used as a tool to apply the factor method in practice.