Larch

Also called: european larch, larix

Larch is a resinous timber used for exterior coverings and roof work, while Western larch is also used for rough building wood, poles, railway sleepers and mine timbers.

Recognise the wood

When identifying larch, examine the growth rings and heartwood, the older inner wood of the tree, rather than relying on colour alone. Its heartwood is often darker, and each growth ring can show an abrupt change between earlywood and latewood, the less dense and denser portions formed during a season. Round or half-round larch can also be used in roof work, with the flatter half-round form giving a more level surface for shingles.

Weather and resin

Larch has been used for exterior coverings because its resin can harden at the surface as the wood weathers. Tredgold (1871) described a covering that darkened as resin accumulated and said the resin resisted weather. That historical behaviour is not a promise that every larch board needs no finish or treatment.

Western larch uses

Western larch is used for rough structural timber, planks and boards, railway sleepers, the crosswise supports beneath rails, and mine timbers. Its poles were adopted for their size, shape and strength, but poles intended for use in most areas require preservative treatment along their full length. Select adequate sapwood, the younger outer wood, thickness and season the pole before treatment, as required for that pole use.

Choose for the setting

Keep the species and end use together when choosing stock. An exterior covering, a Western larch structural board, a sleeper and a treated pole have different requirements, so do not transfer the pole specification to every piece of larch.