Carbon storage and supply sustainability are the environmental benefits driving the renaissance in the use of wood as a construction material. And it is another environmental factor – climate change – that is likely to drive a complementary growth in the use of pre-treated wood. Pre-treatment combats any potential for decay or wood boring insects and makes construction timber highly durable for 60 years and more.
BSI moves to adapt British Standards for climate change
A warmer, wetter more extreme climate for the UK is now regarded as inevitable according to Defra’s Climate Projections. It is also inevitable that more extreme weather patterns will increase the potential for fungal decay and insect attack in components made from un-treated softwoods of low natural durability. Roofing timbers exposed to wetting from leaks are particularly vulnerable. Almost every stick of softwood timber currently used in roof construction today is untreated. When it costs just £30 to pre-treat the volume of timber required for a typical house to use unprotected wood seems like folly. The Climate Change Act 2008 requires that public and statutory organisations take action to adapt to the more extreme weather patterns predicted by Defra. The British Standards Institution (BSI) has identified thirteen potential climate change impacts on standards that need to be addressed if a building is to have a long and useful life. As a consequence, BSI has instructed the committees responsible for the content of all British Standards to review the implications of climate change impacts and incorporate new guidance where appropriate.
Pre-treatment no longer an optional extra
BSI Committee B515 deals with the wood preservation standard, BS8417. B515 Chairman, Dr Chris Coggins says that the consideration of more extreme weather conditions are not included in the current 2014 version of BS8417 but this is likely to change sooner rather than later: “Improved guidance on timber protection standards to meet climate change impacts are essential.” says Coggins who has confirms that following the recent publication of BS EN 350: 2016 relating to the durability of certain species and the service life expectations of exposed heartwood then a review of BS8417 will follow in 2017. WPA Director Steve Young says that WPA will be making a strong case for moving the pre-treatment of some constructional timber components from ‘optional’ to ‘essential’.
He says: “ Building designers cannot afford to wait for climate change to reveal its full effects over time, they need to act now by specifying timber that is fit to take on the likely challenges to its long term performance and particularly the risk posed by the spread of termites and House longhorn beetle caused by a warmer climate.”
Warmer climate means an increased threat of insects
Termites have spread from southern Europe through France and Germany and are now found in Calais. Occasional isolated outbreaks have occurred in the UK, the most recent being in North Devon. The Government has funded extensive attempts to eradicate this outbreak but without success. It is probably only a matter of time before termites become a threat in Southern England. Although the House longhorn beetle is active in North West Surrey and all softwood roofing timbers in that area must be treated, outbreaks in other areas UK are not unknown. WPA warns that the spread of House longhorn beetle and termites are likely to be an inevitable consequence of a warmer UK climate.
This should not come as a surprise. WPA first published a Climate Change Guidance Note in 1996. This highlighted the increased risk to non-durable timber from insects like termites and House longhorn beetle and from damp penetration caused by driving rain, damaged roofs, condensation and flash flooding. About the same time, BRE also published a report on climate change impact on UK Building Regulations which also highlighted the potential spread of termites, House long horn beetle and other insects. These early warnings fell on deaf ears.