Plywood is the wood based panel showing the best physical and mechanical properties for application under moist construction conditions. Appropriate physico-mechanical durability for exterior applications in transportation or construction systems can be guaranteed by assessment of the glue bond quality and mechanical characteristics. However, due to the fact that mainly non-durable wood species are used for plywood production, there is a need to specify the biological durability of plywood in relation to service life.
With the European standard ENV 12038 a tool is available to evaluate the intrinsic biological durability of plywood material. According this standard plywood has to be tested against wood rotting basidiomycetes using a test procedure equivalent to the EN 113 procedure for the assessment of wood preservatives when testing of solid wood.
Testing a large amount of different commercial plywood products according to this standard showed that the test procedure is too severe, offering no possibility to differentiate between panel types (e.g. the influence of a coating could not be distinguished). To be able to use the ENV 12038 as an aid for service life prediction the test procedure needs to be adapted and the results need to be linked to data collected during outdoor field testing.
Service life prediction of plywood requires a combination of durability testing and evaluation of moisture related properties, and relates this to data collected during outdoor field testing and in service data (derived from e.g. surveys).
Furthermore there is a need to identify a simple methodology to interrelate product properties and intended service life for different use class conditions. This paper suggests an approach to enable implementation in practice for plywood.
Keywords: plywood, service life prediction, moisture dynamics, fit for purpose, ENV 12038