Radiata Pine

Description

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.

Performance

Durability

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.

Mechanical Properties

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 standardised 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:

Machining

Machining tests have confirmed that radiata pine compares favourably 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. A comparison with some North American species is shown in the following table:

For further information refer to the following documents and links:

ITM Timber Treatment - Word document

BRANZ treatment diagrams - Printable PDF

BRANZ timber treatment and guide to framing - Printable PDF

Department of Building and Housing website: timber treatment

Formaldehyde - Printable PDF

Considerations

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.

Applications

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;
• mouldings;
• trim;
• panelling.

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.

Case study

Fale Pasifika

The versatility of Glulam radiata pine once again enabled the most cost-effective solution to a complex structure. Established forms of construction, which are no longer possible using traditional materials, can be effectively replicated using manufactured glulam.

This project required an authentic look and feel to the traditional fale design, including the need for concealed joints.

The main 200mm diameter curved glulam frames – each member 14m long were hand planed in the factory to achieve the rounded finish.

Architect:     Jasmax

Structural Engineer:     H.L.K. Jacobs

Availability

Suppliers

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 Agriculture and Forestry (MAF) 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.

The National Exotic Forest Description 2006 from MAF states:

“About 62 percent (993 000 hectares) of the radiata pine planted forest estate is, or is expected to be, pruned to a height of at least four metres.

Approximately 11 percent (110 000 hectares) of pruned radiata pine is older than 25 years, while 17 percent (173 000 hectares) of pruned radiata pine is between 21 and 25 years old. Seventy-two percent (710 000 hectares) of the pruned radiata pine is 20 years old or under.

The area of production thinned forest has declined over the last decade.

Approximately 16 percent of the radiata pine planted forest currently is, or is expected to be, production thinned.

In 1995, 28 percent of the radiata pine forests was, or was intended to be, production thinned.

Production thinning of the radiata resource has decreased in the Central North Island region from 65 percent in 1995 to 22 percent in 2006.

Information collected in the 2006 survey indicates that 60 percent of the forest resource is first-rotation forest, 30 percent is second or subsequent rotation, while information is incomplete for 10 percent of the estate.

Of the identified first-rotation forest, 57 percent is aged 15 years or under.”

Source:

A National Exotic Fofestry Description 2006, Ministry of Agriculture and Forestry