The durability and service life of timber products can be enhanced by impregnating the cells with stable preservatives that act to repel wood destroying insects (such as termites, white ants and borers), and breaking down fungi spores that lead to wood rot.

The impregnation process can vary depending on the timber species, preservatives, carrier agents and treatment hazard level - but can include dipping, spraying or vacuuming the carrier agent into the timber substrate in a high-pressure environment.

Timber treatments are primarily focused on protecting the sapwood. The sapwood of all species is considered non-durable (because of its life-supporting starches and sugars) and is comparatively easily penetrated by preservatives. It is not possible to effectively treat the heartwood of many timber species, as heartwood cells contain extractives that prevent the uptake of preservatives.

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