Eucalyptus hardwood has a distinct reddish to brown color. Some say eucalyptus wood can even stay in wet environments for 10 years without any decay. Eucalyptus sapwood is pale cream. Its grain has a nice pattern that not many other trees have.
Eucalypt timber has several appealing characteristics. It is strong, dense, offers attractive colour choices, and the timber of some species has natural durability.
Quick Facts
Botanical name: Eucalyptus spp
Other common names: Eucalypts
Strength: Eucalypt timber has good strength properties.
Durability: The heartwood of all the blue gum and stringybark species are durable in ground contact, lasting 15 to 25 years in ground contact and up to 40 years out of ground contact, giving an equivalent durability of H3.2. The ash group species are only moderately durable, lasting 5 to 15 years in ground contact giving an equivalent durability of H3.1.
Finishes: The dry timber finishes well, and takes all types of stains and paints. The higher density species may be difficult to glue, e.g. E. muelleriana.
Working properties: Difficulties with eucalypts relate mainly to the sawing of logs, where growth stresses may be a problem, and with drying, as some species are collapse-prone.
Appearance: The heartwood of the blue gums, E. saligna and E. botryoides is dark pink to reddish brown with a paler sapwood. The heartwood of the stringybark group species is yellowish-brown with a pink tinge, and the sapwood paler. The heartwood of E. fastigata is predominantly pale brown with occasional purplish flecks. E. obliqua looks very like European oak. The heartwood of E. regnans and E. delegatensis is pale pink or light brown that is sometimes difficult to differentiate from the pale sapwood. It has a moderate-coarse texture and straight grain.
Durability
| Durability class 1 | Durability class 2 | Durability class 3 | Durability class 4 | |
|---|---|---|---|---|
| Description | Very durable | Durable | Moderately durable | Non-durabale |
| Hazard class | H4 | H3.2 | H3.1 | H1.2 |
| Life expectancy in ground(yrs) | >25 | 15 – 25 | 5 – 15 | 0 – 5 |
| Life expectancy above ground(yrs) | >40 | 15 – 40 | 7 – 15 | 0 – 7 |
| Botryoides | Delegatensis ** | Gunnii | ||
| Globoidea | Globulus * | |||
| Microcorys | Obliqua# | |||
| Muelleriana | Regnans# | |||
| Pilularis | Fastigata#~ | |||
| Saligna |
The correspondence between durability class and hazard class is made assuming that structural members will be larger than the 50x50mm stakes used to establish durability class and that timbers used out of ground contact will be provided with some kind of surface coating or are used in a non-horizontal application where water quickly drains off.
In use as decking, which is horizontal and uncoated, the service life is 15 rather than 50 years because it is easily replaced and not a serious safety concern.
Eucalypt heartwood cannot be treated with waterborne preservatives. The heartwood of all the blue gum and stringybark species are durable in ground contact, lasting 15 to 25 years in ground contact and up to 40 years out of ground contact.
The ash group species are only moderately durable, lasting 5 to 15 years in ground contact.
NOTE: The information in this page has been extracted from New Zealand wood database. For details click here.