Western larch

Category: Softwood
Region: Interior
Title: Western larch (Larix occidentalis)

Western larch is produced predominantly as part of the Douglas-fir-larch species mix. Its properties are similar to Douglas-fir so the species are sometimes sold mixed. Western larch is attractive, and some high-grade material is used for interior finish products.

Western larch grows in valleys and on the lower slopes of mountains in BC’s southern interior. It produces hard, strong wood that is used to produce heavy timber for products such as planks and boards, poles, railroad crossties and mine timbers.

Where it grows

Western larch grows in valleys and on the lower slopes of mountains in BC’s southern interior. It needs full sunlight so does best in the open. While it usually grows in mixed stands with Douglas-fir, western hemlock and lodgepole pine, it can be found in pure groups after a severe wildfire and grows well on fire-blackened soil.

Low temperatures limit the distribution of western larch because it continues to grow from spring through to September so it is sensitive to frost damage. Most other evergreens stop growing in July.

Identifiable characteristics

Western larch is a medium- to large-sized tree that can grow up to 80 metres tall with a diameter of 1.5 metres. It can live as long as 900 years. The tree has a branch-free stem over much of its length, with a pyramidal crown and horizontal branches. The bark is reddish-brown and deeply furrowed with flaky ridges.

New needles are soft green, turning golden yellow in the fall. They are broadly triangular in cross-section and are found in long clusters of 15 to 20 on stubby, woody projections which remain on the twig after the needles fall. Seed cones are elongated and red to reddish-brown. The scales have white hairs on the lower surface and prominent, long slender flowers. Pollen cones are yellow.

Common uses and applications

Western larch produces heavy, hard and strong wood that is used in building construction for rough dimension, small timbers, planks and boards, poles, railroad crossties and mine timbers, and pulp. It is visually appealing so some high-grade material is manufactured into interior finish, fine veneer, flooring, sashes and doors.

Private Residence
Photo credit: Peter Powles

Commercial properties

The properties of western larch are similar or even superior to those of Douglas-fir, and the species are sometimes sold mixed. Western larch wood is stiff, moderately strong and hard, as well as moderately heavy. The wood dries well but with some tendency to warp and surface check. It works fairly readily with only a small blunting effect on cutting edges. It turns, planes and shapes well, and can be sanded to a smooth finish. The wood glues well, has moderate nail and high screw holding ability, and takes a good finish.

Did you know?

The thick bark of western larch and its habit of shedding lower branches make it resistant to wildfire.

Commercial availability

Western larch is produced predominantly as a Douglas-fir-larch species mix in structural grades according to National Lumber Grades Authority (NLGA) rules for dimension lumber. Select Structural, #2 and better, and stud grades are the most common grades produced, and specialty in-house grades and export grades are also available.

Western larch is used for lamstock because of its high-strength properties. Appearance grades are also produced according to NLGA rules. Clears, shop lumber and moulding stock are most common, though there are many potential appearance grades that can be produced.

Western larch lumber is dried according to end-use and customer specifications. Kiln drying inhibits natural staining of the wood, improves its strength and stiffness, enhances its appearance, and increases its resistance to decay and attack by insects.

Private Residence
Photo credit: Peter Powles

Western larch – physical properties

Density (kg/m3)Green549
Air dry600
Specific gravity (12% m.c.)Standard0.55
Hardness (N)Side4210
End5670
MOE (Mpa)Green11400
Air dry14300
MOR (Mpa)Green59.8
Air dry107
Compression parallel (Mpa)Air dry60.9
Compression perpendicular (Mpa)Air dry7.31
Shear (Mpa)Air dry9.25
Cleavage (N/mm width)Air dry48.0
ShrinkageRadial (OD)5.1%
OD = oven dryTangential (OD)8.9%
air = air dry 12%Volumetric (OD)14%
Volumetric (air)8%
Tang / rad ratio1.8

Western larch – visual properties

Colour
HeartwoodDeep reddish-brown.
SapwoodYellowish-white to yellowish-brown, narrow.
Heartwood / sapwood contrastSharply defined.
Latewood / earlywood contrastThere is considerable contrast in colour between the earlywood and latewood.
Grain
The wood is generally straight-grained.
Figure
Plainsawn lumber or rotary-cut veneer: conspicuous growth ring.
Quartersawn lumber or quarter-sliced veneer: distinct growth ring stripe.
Other: closely resembles douglas-fir.
Knots
Knots are common but generally small and tight.
Other
Wood of western larch is stiff, moderately strong and hard. It splits easily and is subject to ring shake.

Western larch – working properties

ProcessPerformanceComments
Machining
PlaningModerateRecommended planer settings: 20° hook angle and western larch 16 or 20 kmpi (knife marks per inch).
TurningHigh to medium surface qualityTurns exceptionally well on a rotary-knife lathe.
SawingEasy to work with toolsResin exudation can sometimes negatively affect blunting effect.
BoringGood to moderateGood boring quality with both brad point bits and moderate boring quality with single twist bits.
MortisingModerateGood mortising quality when using a hollow chisel mortise. Common mortising defects: splintering on the out-going side of the mortise and crushed grain inside the mortise.
ShapingGood shaping quality
VeneeringN/A
SandingGoodExcellent sanding properties.
Fastening
ScrewingGoodAverage screw rentention: 547 lb.
Nail retention ExcellentTends to split in nailing. Excellent holding once nailed. Surpasses douglas-fir.
Lateral nail holdingGoodComparable to douglas-fir.
GluingGlues satisfactorilyBonds well with a fairly wide range of adhesives under a moderately wide range of bonding conditions.
Finishing
StainingModerateWild grain is very visible when a dark stain is used. Resin content can make staining more difficult.
PaintingAverage to good paint holding abilityResin content can make painting more difficult if the resin is not set during drying.
LacqueringGoodRecommend multiple clear coats or a high build clear finish to achieve smooth texture. Performed well in the tape test (i.e. edges of the cuts were completely smooth; none of the squares of the lattice was detached) and in the pull-off test (i.e. average strength of 29 kg/cm2).
WaxingGoodBest results are obtained when using light- to medium-coloured waxes (e.g. mellow pine or chestnut).
Drying
Ease of dryingModerately easy Dries fairly well, but with some tendency to warp and surface check.
Durability
Natural decay resistanceModerately durableShould not be used in applications with prolonged ground contact.
TreatabilityImpermeable to extremely impermeable Can be improved by incising.