Timber in Future Construction By Richard Harris- Professor of Timber Engineering - Bath University
The use of timber reaches back into our past. The word, timber, has its origins in Old English, where it is used to mean building structure. The word has evolved, coming to mean the building material, trees suitable for building and wood in general. This link between trees and buildings is very important – it is because timber is derived from living forests that it can be sustainably sourced. Environment Industry Magazine (Alasdair McGregor “Playing by the Book” Oct/Nov 2010) has recently covered the sustainable sourcing of timber. Use of material from the same woodlands over many centuries demonstrates that timber, if managed appropriately, is a sustainable material. Thus it is a material we can move forward with, in the confidence that it will be available in the future. There will, however, be competing demands on the resource.
• Construction. Structure both as sawn timber and in engineered products. Also joinery timber (doors, windows, floor finishes).
• Paper. Although much paper derives from recycled content, there are still large volumes of new wood used to make paper.
• Fuel. Historically the largest use of timber has been as fuel. With the need to return to renewable energy sources, there is strong demand for fuel wood for both large-scale energy generation as well as use at a domestic scale.
• Bio-products. With the eventual inevitable reduction in oil production, wood, with other crops, will become a primary source for the chemicals to make those products that are currently produced from oil. Oil is derived from plants and is a concentrate of hydrocarbons. Thus wood can be used to make composites, bio fuels (biodiesel, ethanol, bio-oils and gas) as well as aromatics, waxes, solvents, polymers and other products essential to modern manufacturing.
There is a need, especially in a densely populated area such as the UK, for forests to deliver environmental and social benefits. Clearly there will be an increasing demand for an adequate supply of timber, and this means that more woodland should be planted for longterm commercial benefit. Forestry is a long-term occupation but current short-term policies are not leading to the healthy forest we will need in fifty years from now. Grant aid to woodland planted for environmental and social benefits alone tends to encourage non-productive woodland. A mis-match between agri-environmental schemes and woodland grants disadvantages woodland. Well directed grants would lead to support for activities
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that make woodland self-sustaining. For example, grants to encourage thinning would stimulate production for wood-fuel and enhance biodiversity, whilst improving public access, wildlife habitat and the longterm potential for good quality trees. Grants to encourage the planting of high quality seed of appropriate species for the woodland location would yield longterm benefits – too often foresters look at a stand of trees at fifty years and say “if only they had planted seed with a better provenance”! The UK has forest cover of 12% of its area; this is one of the lowest in Europe. Stourhead Estate (Figure 1) is an exemplar of a forest that creates biodiversity, public access as well as a supply of quality timber – there is room for much more of this type of woodland in the UK.
Figure 1 Stourhead Estate, Wiltshire (Photo Richard Harris – The University of Bath)
Figure 4
Currently UK construction is moving towards a much greater use of timber in construction. It is this move to using timber in construction, which should be a pointer towards the need to plant more productive forests. Forestry needs longterm planning and investments. The changes in the construction industry should be taken as a pointer towards the need for the UK to develop its forests at a time of rising demand.
The UK falls behind other areas of the world in the use of timber for domestic construction. There is a revival in the use of traditional carpentry, which includes the use of un-seasoned oak-framing, with traditional joints, to make sophisticated modern homes. The use of simple load- bearing stud walls for general housing is on the increase, as builders, developers and occupiers recognise the advantages.
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