Timber modification is an emerging commercial reality. Timber that has been acetylated, thermally modified or
furfurylated is now readily available. However, the assessment of the effectiveness of each modification type in
enhancement of durability, and therefore the effect on service life, has yet to be fully established. The paper includes
a summary of the key points necessary to understand the mechanisms of protection given to wood by such
modification. This paper also brings together the current work on the assessment of the durability of three types of
modified wood and the effects that each has on the service life of timber structures, and addresses the harmonisation
of standards in this field. This will allow for future development of appropriate standards for utilising these novel
timber products, and therefore improve service life prediction and confidence when designing with these materials.