Engineered products

Trusses

More prefabricated pine trusses should be used for domestic roofing. The product is more efficient than a stick-built hardwood roof with less waste. Native forest timbers can then be used for value added purposes such as furniture or flooring.

Bridges

There are about four hundred timber bridges in the south-west of the State, many of which are in State forests. Timber bridges are engineered structures, and one requirement is that regular inspections are made to ensure that fungal or termite attacks have not affected the structure.

Wide spans

Timber engineering in North America and Europe is significantly more advanced than in Australia. As an example, sporting venues use laminated beams with spans of over 100 m because of the high strength/weight ratio that gives timber a significant advantage over steel.

Poles/posts

Western Power has over 800 000 wooden power and transmission poles in the State, most of which have a long service life. Jarrah and WA blackbutt (Eucalyptus patens) were commonly used in the past, but in recent years karri had supplied over half the annual requirement. This year significant numbers of pine poles have been supplied to Western Power. With an increasing proportion of the States native forests in Conservation Areas or National Parks, fewer poles are available. In the Perth metropolitan area, power supplies are systematically being installed underground, mainly for aesthetic purposes. Wooden poles are much cheaper than concrete and require less energy in production, and would still be required for country areas where underground costs would be prohibitive.

While many species have naturally durable heartwood, the sapwood is non-durable and is therefore made durable by treatment with copper-chrome-arsenic preservative using a vacuum/pressure process.

Sleepers

The State Government has instructed Westrail to cease utilisation of native timber for new railway sleepers, and shift to a total reliance on alternative materials. The alternative sleeper products are concrete and steel. In manufacturing concrete sleepers, considerably more energy (generated from fossil fuels) is required, and track-laying costs per kilometre are perhaps twice those of laying timber sleepers. Steel sleepers also need considerable energy in manufacturing.