1. Head of Composite Group, Centre for Timber Technology and Construction, Building Research Establishment, Garston, Watford, Herts WD25 9XX, U.K. (corresponding author).
2. Director of Construction Division, Building Research Establishment, Garston, Watford, Herts WD25 9XX, U.K.
3. Associate, Centre for Timber Technology and Construction, Building Research Establishment, Garston, Watford, Herts WD25 9XX, U.K.
4. Director, Centre for Timber Technology and Construction, Building Research Establishment, Garston, Watford, Herts WD25 9XX, U.K.