Radiata Pine

Botanical Name: Pinus Radiata

Radiata pine’s sapwood is white to pale yellow, but often indistinguishable from the heartwood, which is light brown to yellow. The grain is usually straight, apart from a central core of 100mm, which can twist if the moisture content of the timber changes. The texture of radiata pine is fine, but uneven, and knots are common. The timber is fairly soft and has a low density, often with very wide annual growth rings.

Radiata pine is easy to work except for the knots, and it nails satisfactorily. Apart from the core, it is easy to dry, and because it dries quickly, it is usually kiln dried directly from being green. During the warmer months it is very susceptible to bluestain. There can be problems with timber that is high in resin content: it can be hard to glue, and knots, resin streaks and latewood can emit enough resin to mar exterior coatings. Timber that is high in resin should be used for structural purposes only. It is not suitable for steam bending as it is hard to obtain a smooth curve. It readily accepts preservatives, which provide protection to Hazard level 6 (the highest level).

Density New Zealand 490 kg/m3
Strength Groups S7 unseasoned; SD6 seasoned
Stress Grades New Zealand: F4, F5, F7 (unseasoned), F5, F7, F8, F11, F14 (seasoned) when visually stress graded in accordance with AS 2858-2001
Joint Groups JD4 seasoned
Shrinkage to 12% MC 5.1% (tangential); 3.4% (radial)
Durability Above-ground Class 4 – life expectancy 7 years
Durability In-ground Class 4 – life expectancy 5 years
Lyctine Suceptibility Untreated sapwood susceptible to lyctid borer attack
Termite Resistance Not Resistant
Preservation Plantation grown trees have a higher portion of sapwood, which readily accepts commercial preservation impregnation. The heartwood of radiata pine also accepts some preservative impregnation but for practical purposes it is considered untreatable as results are unreliable.
Seasoning To avoid distortion, framing sizes should be high temperature dries. Boards may be air-dried or kiln-dried at conventional or high temperatures.
Hardness Soft (rated 5 on a 6 class scale) in relation to indentation and ease of working with hand tools.
Machining Machines and turns well but planer blades should be kept sharp to avoid surface ridging.
Fixing Nails may occasionally follow the growth rings. Nailing guns give good results.
Gluing Differential glue absorption can occur between earlywood and latewood but this is rarely causes problems.
Finishing Will readily accept, paint, stain and polish.