Nz Radiata Pine

Radiata Pine has a number of structural uses including decking, fencing, exterior cladding, window sashes, pergolas, landscaping, shingles, barge boards and exterior trim.

Untreated, it can be used for furniture, moldings, trim and paneling. Panel products, such as plywood, MDF and laminated veneer lumber, are also available from radiata pine resources.

Radiata pine is grown commercially in New Zealand as an exotic species from the Monterey peninsular in California. The majority of plantation forests are Forest Stewardship Council certified. The Resource Management Act 1991 places several requirements on forest growers, including the need to consider employment, social, cultural and environmental impacts. This results in a level of environmental responsibility that does not exist in other countries. In addition, 80 percent of plantation forest owners have adopted the New Zealand Forest Owners’ Environmental Code of Practice for Plantation Forestry (2007). The code of practice covers areas including the protection of waterways, endangered species, historical sites, sediment control and the management of fuel, oil and wastes. Afforestation with Radiata pine rehabilitates previously farmed soils by reducing compaction caused by stock, with soil condition improving with subsequent rotations.

Radiata pine heartwood is an even, light brown to chestnut brown colour, the sapwood is creamy white. Resin canals are present as fine brown lines in the latewood part of the growth rings, especially on radial surfaces, and these can be a handy means of identification. Texture is fine but uneven.

The contrast in colour and texture between early and latewood bands (growth rings) in flat-sawn timber is relatively moderate compared with other pines and conifer species. The veneer has a moderate-to-high lustre. Common features in most Pinus species, including radiata pine, are: knots, cone stem holes and pine-needle flecks. Radiata pine is a versatile and readily available timber, suitable for a wide variety of end-use applications. It produces wood that is very acceptable to the construction industry. The bark is rich in tannins and suitable for use in the manufacture of adhesives; it also contains some wax, which may have possible use in water repellents. It is suitable for framing, industrial uses, posts, cladding, decking, interior finishes and trims, and everyday furniture. Radiata does not begin to form heartwood until it is about 15 years old and forms it at the rate of one ring every two years. Most of the wood, therefore, is easy-to-dry and easy-to-treat sapwood. This is an advantage over many Northern Hemisphere conifers, which are largely heartwood.

Low level treatment such as boron is recommended to future-proof against insect attack in areas completely protected from moisture, such as furniture and the framing of internal walls of buildings. Because radiata pine is easily treated, the timber can be obtained to give appropriate durability in any of the Hazard Classes from H1 to H6.

At 12 percent moisture content, the density of radiata pine varies from 560 kg/m3 from low-altitude growth sites from the Waikato northwards, to 460 kg/m3 in timber supplied from Otago and Southland. The average density figure for the whole country is 500 kg/m3.

Most of the density variation is related to the average temperature during the growing season: the cooler the site, the lower will be the wood density, hence the decrease with altitude and latitude. Please note these comparative measures of strength are “laboratory” values using standardized short lengths of clear timber.

These will not be the same strength properties as structural lengths of timber. For the properties of structural length timber please see the tables under the structural design section.

Mechanical properties vary with density, and the presence of knots, sloping grain and other natural features. For timber free of these natural features (clear wood), of average density, from trees felled at 30 years of age and the average properties measured on small specimens (20 x 20mm cross section) are:

# Modulus of elasticity : 8.23 GPa
# Bending strength : 85.8 MPa
# Compression strength parallel to the grain :36.8 MPa
# Side hardness (refers to indentation) :3.64 kN
# Shear strength parallel to the grain : 11.6 MPa
# End hardness : 4.76 kN

Machining tests have confirmed that radiata pine compares favorably with a variety of other internationally traded timbers. Most wood products require machining in one form or another.

The machining characteristics of any wood species can be as important as its strength, hardness or durability in deciding which species is best for a given end use.

The most common form of machining is planing, closely followed by shaping and turning. Cross-cutting, boring, mortising and sanding are also common types of machining.

The corewood area – perhaps four to five growth rings in diameter from the central pith – contains low-density wood that shrinks excessively in a longitudinal direction; it also contains spiral grain, which can lead to twisting in sawn timber.

The grading rules for Pinus species take this aspect into account. Less desirable features to watch for when working with this timber include:

# resinous pockets;
# checking marks;
# darker orange bands of compression wood and presence of pith.

Radiata pine is plentiful, and readily available from a wide variety of suppliers. Refer to the Suppliers database or go to the NZ Farm Forestry Association Marketplace.

Forest statistics Ministry of Primary Industries statistics show that today, there is an estimated forested area of 1.6 million hectares of radiata pine, 89% of the total plantation forested area. Visit the Ministry of Primary Industries website for further information and statistics or FOA Facts and Figures.

Treated radiata pine is suitable for the following applications: structural uses, decking, fencing, exterior cladding, window sashes, pergolas, landscaping, shingles, barge boards, exterior trim.

Interior uses for untreated timber include: furniture, moldings, trim, paneling.

Strip and tongue-and-grooved flooring is unsuitable, unless from hardened radiata pine products. Panel products, such as plywood, MDF and laminated veneer lumber, are also available from radiata pine resources.