Ask most builders what softwood they would use for a deck and they will say cedar or pressure-treated pine. Ask them about siding and they will say cedar again, maybe Douglas fir. Ask about flooring and you will hear pine or fir. Almost nobody says Western larch — and that is a shame, because by nearly every measurable property, Western larch outperforms all of them. It is harder, stronger, more rot-resistant than most softwoods, and it has a rich, warm color that rivals many hardwoods. Yet it remains one of the least known species in the Pacific Northwest lumber market.
At Boise Lumber, we have been advocating for Western larch for years. We carry it in multiple dimensions and grades, and every customer who tries it comes back for more. This article is our case for why Western larch deserves to be on your shortlist for decking, siding, flooring, timber framing, and just about any application where you want a softwood that performs well above its weight class.
What Is Western Larch?
Western larch (Larix occidentalis) is a large deciduous conifer native to the mountains of the Pacific Northwest and northern Rocky Mountains. Yes, deciduous — larch is one of the few conifers that drops its needles every fall, turning a brilliant gold before shedding. It grows at elevations between 2,000 and 7,000 feet across northern Idaho, western Montana, northeastern Oregon, and southeastern British Columbia. The largest specimens can reach 150 feet tall and 3-4 feet in diameter, with lifespans exceeding 500 years.
In Idaho, Western larch is particularly abundant in the forests of the panhandle region — the areas around Coeur d'Alene, Moscow, and the Clearwater drainage. It thrives in well-drained mountain soils and is often found growing alongside Douglas fir, grand fir, and ponderosa pine. Its thick, fire-resistant bark makes it one of the most resilient trees in fire-prone landscapes, which is one reason why mature larch stands persist in areas where other species have been wiped out by repeated wildfire.
Despite its abundance in Idaho's forests, Western larch has historically been overshadowed in the lumber market by its more famous neighbors, Douglas fir and western red cedar. Part of this is simply marketing — cedar and fir have had decades of brand recognition built by industry associations. Part of it is supply chain — most sawmills in the region are set up to process fir and pine, and larch requires slightly different handling due to its density and resin content. But the wood itself is exceptional, and those who know it will tell you it is one of the best-kept secrets in the softwood world.
Physical Properties: The Hardest Softwood in North America
Here is the fact that turns heads: Western larch has a Janka hardness rating of approximately 830 lbf. For context, that is harder than many species commonly sold as "hardwoods." It is harder than basswood (410), butternut (490), aspen (350), and even yellow poplar (540). It is in the same neighborhood as black cherry (950) and not far below black walnut (1,010). Among North American softwoods, nothing comes close — Douglas fir rates at 660, western red cedar at 350, and ponderosa pine at 460.
This hardness translates directly to durability. Larch flooring resists dents and wear significantly better than pine or fir flooring. Larch decking stands up to foot traffic, furniture, and the freeze-thaw cycles of Idaho winters better than cedar. Larch siding resists impact damage from hail, falling branches, and the general wear of weather exposure.
Beyond hardness, Western larch has excellent structural properties. Its modulus of elasticity (stiffness) and modulus of rupture (bending strength) are among the highest of any softwood species. A larch beam can carry loads comparable to Douglas fir at the same dimensions, and it does so with less deflection. The wood is also remarkably straight-grained, which means it machines well, holds fasteners tightly, and resists splitting better than many competing species.
The density of Western larch averages about 36 pounds per cubic foot at 12% moisture content — denser than Douglas fir (34 lbs/ft3) and significantly denser than cedar (23 lbs/ft3). This higher density is directly responsible for its superior hardness and strength, and it also means that larch has better thermal mass, which can be a useful property in building applications where temperature regulation matters.
Natural Durability and Rot Resistance
Western larch heartwood is rated as moderately durable to durable in terms of natural decay resistance. The heartwood contains extractives — primarily arabinogalactan, a water-soluble polysaccharide — that provide natural resistance to fungal decay and insect attack. While it does not quite match the legendary durability of old-growth western red cedar heartwood, it significantly outperforms Douglas fir, pine, spruce, and hemlock in ground-contact and exterior applications.
In practical terms, this means untreated larch heartwood can be used for exterior applications like decking, siding, fencing, and outdoor furniture with a reasonable expectation of longevity — especially in Idaho's dry climate, where the lower humidity reduces the risk of sustained moisture exposure that accelerates decay. Many historic structures in northern Idaho and Montana were built with larch, and examples from the early 1900s are still standing with heartwood members in good condition.
It is important to distinguish between heartwood and sapwood here. Like all species, larch sapwood (the lighter-colored outer wood) has minimal natural decay resistance. For exterior applications, you want boards that are predominantly heartwood — identifiable by their darker reddish-brown color. At Boise Lumber, we sort our larch stock to ensure that exterior-grade material is heartwood-dominant. For more on how we grade and sort our lumber, visit our grading guide.
The Beauty Factor: Color, Grain, and Character
One of the most compelling reasons to choose Western larch is simply how beautiful it is. The heartwood ranges from a warm yellowish-brown to a rich reddish-brown, deepening with age and UV exposure to a handsome amber tone. The grain is tight and straight, with a fine, even texture that takes finishes exceptionally well. When finished with a clear oil or varnish, larch has a depth and warmth that is often compared to cherry or mahogany rather than to other softwoods.
The contrast between the lighter sapwood and darker heartwood can be striking, and some customers intentionally select boards with a mix of both for visual interest. Others prefer all-heartwood boards for a more uniform, rich appearance. Either way, larch brings a level of visual sophistication that pine and fir simply do not offer. It looks like a premium wood because it is a premium wood — it just happens to be priced as a softwood.
Reclaimed larch is particularly beautiful. Boards salvaged from old buildings, mining structures, and railroad infrastructure in northern Idaho often have a silvery-gray patina on the surface with warm reddish-brown tones visible underneath when lightly sanded. The combination of aged surface character and the species' naturally attractive grain makes reclaimed larch one of the most sought-after materials for accent walls, furniture, and architectural details.
How Western Larch Compares to Douglas Fir and Cedar
The three species most commonly considered for premium softwood applications in the Pacific Northwest are Douglas fir, western red cedar, and Western larch. Here is how they stack up head to head.
Hardness: Larch (830) beats Douglas fir (660) by 26% and cedar (350) by 137%. For applications where surface durability matters — flooring, decking, countertops — larch is the clear winner.
Strength: Larch and Douglas fir are comparable in bending strength and stiffness, both significantly outperforming cedar. For structural applications like beams, joists, and rafters, both larch and fir are excellent. Cedar is not typically used for structural applications due to its lower strength values.
Decay resistance:Cedar heartwood has the best natural decay resistance of the three, particularly old-growth cedar. Larch heartwood is moderately durable — better than Douglas fir but not quite at cedar's level. For ground-contact applications or extreme moisture exposure, cedar or pressure-treated lumber is still the safer choice. For above-ground exterior applications, larch is more than adequate.
Workability: Cedar is the easiest to work — it is soft, light, and machines effortlessly. Douglas fir is moderately easy but can be prone to splintering and tear-out around knots. Larch machines well due to its straight grain and fine texture, but its density means it requires sharper tools and slightly more effort. Pre-drilling for screws is recommended with larch to prevent splitting near edges.
Price: Larch is typically priced between Douglas fir and cedar, making it an excellent value given its superior hardness and durability. In Idaho, where larch is locally harvested, it can be even more competitive — especially at Boise Lumber, where we source larch directly from Idaho mills. For complete species comparisons, check our wood species guide.
Ideal Applications for Western Larch
Given its combination of hardness, strength, natural durability, and beauty, Western larch is versatile enough for an impressive range of applications.
Decking:This is where larch truly shines. Its hardness resists denting from furniture and foot traffic. Its natural durability handles Idaho's weather cycles. Its warm color and tight grain look stunning on a deck. Larch decking can be left to weather naturally to a silvery gray or maintained with periodic oiling to preserve the original warm tones. Either way, it outlasts and outperforms cedar decking in everything except the initial ease of installation (larch is heavier and requires pre-drilling).
Siding: Western larch makes excellent lap siding, board-and-batten siding, and channel siding. Its dimensional stability means it stays flat and tight over time, its heartwood resists decay, and its natural color provides a beautiful base for either clear finishes or stains. Many contemporary homes in the Boise foothills and McCall area use larch siding for a warm, natural look that is distinctly Idaho.
Flooring: With a Janka hardness of 830, larch is hard enough for residential flooring in bedrooms, living rooms, and offices. It will develop character and patina over time, and it is significantly more dent-resistant than pine or fir flooring. For kitchens and entryways where durability is even more important, consider a harder hardwood species — but for most residential applications, larch flooring performs beautifully.
Timber framing:The strength properties of larch make it an excellent choice for exposed timber frame construction. Larch timbers have a warmth and richness that complements rustic and contemporary architecture alike, and the wood's straight grain makes it ideal for the precise joinery that timber framing requires. A larch timber frame in a great room or entryway is a showpiece.
Finding Western Larch at Boise Lumber
We carry Western larch in dimensional lumber, decking profiles, siding profiles, and rough-sawn timbers. Because we source directly from Idaho mills, we can often get larch in sizes and grades that are difficult to find elsewhere. If you need a specific dimension or profile that we do not have in stock, our custom milling service can produce it from our larch inventory.
We also carry reclaimed larch when it is available — and it is one of the first species to sell out when we get it. Reclaimed larch from old mining structures, railroad trestles, and agricultural buildings in northern Idaho is some of the most beautiful wood we handle. If you are interested in reclaimed larch, let us know and we can notify you when our next batch comes in.
Western larch is Idaho's wood. It grows in our forests, it built our early structures, and it deserves a place in our modern buildings too. If you have never worked with it, come by the yard and pick up a board. Feel the weight, look at the grain, and compare it to the cedar or fir you were planning to use. We think you will see what we have been saying for years — this is one of the best woods in the West, and it is time more people knew about it.