Buitenhout

Buitenhout is the term used in Dutch for timber that is intended for outdoor use, i.e., wood that is exposed to weather, moisture and temperature fluctuations. The key requirement for buitenhout is durability against decay, rot, fungi and insect attack when left outside without interior protection.

Outdoor uses include decking, fencing, exterior joinery, terraces, garden furniture and other structures exposed to the elements. Selection is influenced by natural durability of the species or by preservation treatment. Buitenhout can be sourced as natural durable wood (hardwoods such as bankirai/kebon, iroko or teak; softwoods like pine or spruce that are treated) or as treated wood that receives protective preservatives or surface finishes.

Two main routes are used to improve outdoor performance. One is choosing naturally durable species or thermally modified wood, which gains decay resistance through processing. The other is pressure-treated or otherwise preservative-treated wood, where chemicals are applied to reduce decay and insect damage. Common treatment systems include pressure or vacuum processes with preservatives (historically CCA, now more often ACQ or copper azole) and newer environmentally friendly options. Finished exterior surfaces (oils, stains, paints) also extend service life by reducing moisture uptake and UV damage.

Durability is often described by class standards (for example EN 350-2) or by the choice of preservative class, with class 1–2 preferred for long outdoor life. Maintenance is important, including cleaning and reapplication of sealants or finishes every few years.

Sustainability considerations include certifications such as FSC or PEFC to ensure responsible sourcing.