Material Use

After 150 years of the unsustainable use of New Zealand’s native timbers, little is now available for general construction purposes. In the 1930s, plantations of various timbers were trialled, with radiata pine considered to be the most suitable for forest production.

While radiata pine is the most common timber used, it is not a durable timber unless treated against insect attack and, more importantly, fungal attack, in order to be suitable for construction in areas where dampness is likely. Radiata pine accepts treatment readily and can be treated with a variety of chemicals to give a range of durability targeted for particular end uses.

Treatment increases cost and risk of pollution from toxic chemicals and makes disposal more difficult. Specifiers should specify treatments that closely match the use and durability required.

Imported timbers are often specified for specialist uses, and care should be taken to ensure they are from properly certified sustainable sources.

The embodied energy figures quoted for timber do not include the production of treatment chemicals. External use of timber in New Zealand buildings is primarily as:

• landscaping timbers (steps, retaining walls, boardwalks)
• foundations systems
• deck structures
• decking
• wall cladding and exterior trims
• roof cladding.

See the Level factsheet on timber.