Wood knowledge Specifying and sourcing timber in construction

Specifying and sourcing timber in construction

The following is an extract from Wood Information Sheet 2/3-10 Timbers – their properties and uses, which had a major update in 2021.

Timber is a versatile material, its properties suited to a very wide range of uses both structural and non-structural. Wood Information Sheet (WIS) 2/3-10 offers an overview of the considerations a specifier should take into account when deciding whether the properties of a timber are suitable for a particular end use.

Specifying timber

While trees capture carbon dioxide from the atmosphere, store carbon as a ‘building block’ of timber and release oxygen back into the atmosphere, timber is both renewable and recyclable. Timber has therefore gained a very welldeserved reputation for being an environmentally friendly and versatile material.

Timber is used widely in a range of applications and evidence of its versatility is all around us. It can be used for numerous external and internal purposes, ranging from structural posts, beams, joists and rafters, to nonstructural external timber cladding, fencing, windows and doors, and interior flooring. It is also used for furniture and specialist uses such as musical instruments and tool handles.

When choosing from the range of timber species available, a specifer should establish which properties are required of the timber to achieve the desired performance for a particular end use.

Sustainable sourcing

Prior to 31 December 2020 and the UK’s final departure from the EU Customs Union and the European single market, timber traded in the UK had to comply with the EU Timber Regulation (EUTR).1 Since 1 January 2021, the UK construction industry must follow the UK Government’s own Timber and Timber Products Placing on the Market Regulations (UKTR).2 While the UKTR has many of the same requirements as the EUTR, it will lead to some changes for timber suppliers. The EUTR requires that timber placed on the European market is supplied in accordance with the relevant national laws of the country of origin. It also requires evidence of supply chain traceability. Under UKTR, operators must collect and demonstrate much more detailed due diligence procedures. They are obliged to ensure there is ‘negligible risk’ of illegally harvested timber entering their supply chains, for example; your timber supplier will have dealt with this requirement.3

Chain of custody certification schemes to support the sustainable sourcing process are available, such as those operated by the Forest Stewardship Council® (FSC®) and the Programme for the Endorsement of Forest Certification (PEFC™). These third-party certification schemes verify that timber suppliers are part of an unbroken ‘chain of custody’ system, which provides proof that the timber used to process or manufacture an end product was sourced from a well-managed forest. Certification labels on the end product demonstrate compliance with schemes such as those maintained by FSC® and PEFC™.4

Some species, notably tropical hardwoods prized for their decorative features, are no longer readily available. For example, rosewood (Dalbergia nigra) is listed under Appendix I to the Convention on International Trade in Endangered Species (CITES), meaning trade is severely restricted, whereas other Dalbergia spp. may be available. For an indication of whether a species is under threat or endangered, refer to:

• Checklist of CITES Species5 • The IUCN Red List of Threatened Species.6

British-grown timber is available for a number of end uses, particularly for sawn timber, particleboard and fibreboard.7 n

Further information

The full version of this Wood Information Sheet is available to buy from bookshop.bmtrada.com.

References

1. Regulation (EU) No 995/2010 of the European Parliament and of the Council of 20 October 2010 laying down the obligations of operators who place timber and timber products on the market

2. www.gov.uk/guidance/regulations-timber-and-flegt-licences

3. More information can be found at gov.uk

4. For more information, see WIS 2/3-58 Sustainable timber sourcing, BM TRADA, 2019

5. http://checklist.cites.org

6. www.iucnredlist.org

7. For more information, see WIS 2/3-67 Specifying Britishgrown timbers, BM TRADA, 2022. This WIS contains a detailed set of species data sheets for a number of Britain’s timbers including oak, ash and Douglas fir

8. For more information, see WIS 2/3-63 Modified wood products, BM TRADA, 2021