Also see:
3.37.2.5 Durability
Timber shall be of suitable durability.
The following timber members should be preservative treated or have adequate natural durability in accordance with Chapter 3.3 ‘Timber Preservation (natural solid timber)’:
Table 4: Durability options for the following components
Notes
1. Where natural durability is used in lieu of preservative treatment, timber must be specified and selected as being heartwood only. Natural durability classes for the
heartwood of commonly used timbers are available in BS EN 350 and Table 2 in Chapter 3.3.
Where the pitched roof is to include a fully supported weatherproofing membrane (ie, impervious coverings such as single ply membranes, bituminous membranes, etc) or continuous metal coverings, the risk of condensation is increased. The timber components listed in Table 5 should be preservative treated or have adequate natural durability.
Table 5: Durability options where fully supported weatherproofing membranes and continuous metal coverings are used
Notes
1. Where natural durability is used in lieu of preservative treatment, timber must be specified and selected as being heartwood only. Natural durability classes for the
heartwood of commonly used timbers are available in BS EN 350 and Table 2 in Chapter 3.3.
Last updated: 2nd January 2024