Best Woods for Outdoor Projects

Wood doesn’t last outside. Water swells fibers. Fungi digest cellulose. Insects bore tunnels. Sunlight bleaches and cracks the surface.

Unless you choose the right wood.

Some species have natural resistance—chemicals in their heartwood that repel decay organisms and insects. Others can be treated to gain resistance. Knowing the difference saves money, time, and frustration.

What Makes Wood Decay-Resistant

Natural Preservatives

Certain trees produce chemicals that make their heartwood hostile to fungi and insects:

Tannins: Astringent compounds that interfere with fungal enzymes.

Oils and resins: Physical barriers that prevent moisture penetration.

Alkaloids and phenols: Toxic to decay organisms.

These compounds concentrate in heartwood—the dead, central portion of the trunk. Sapwood (the living outer layers) has little natural resistance regardless of species.

When buying naturally decay-resistant wood, you want heartwood, not sapwood.

Physical Properties

Beyond chemistry, physical properties affect durability:

Density: Denser wood absorbs less water and provides less oxygen for decay organisms.

Extractive content: Woods with more natural preservatives last longer.

Permeability: How easily water penetrates. Less permeable means more resistant.

The Naturally Resistant Woods

Western Red Cedar

The most common choice for outdoor projects in North America.

Resistance: High. Heartwood lasts 15-20+ years ground contact, longer above ground.

Appearance: Reddish-brown heartwood, creamy sapwood. Weathers to silver-gray.

Workability: Soft, easy to cut and shape. Accepts finishes well.

Strength: Relatively low. Not for structural loads unless sized appropriately.

Best uses: Decking, siding, fencing, outdoor furniture, planters.

Cost: Moderate to expensive depending on grade.

Cedar works well but isn’t indestructible. Posts in ground contact need replacement eventually. Oil finishes extend life and maintain color; without finish, cedar grays.

Redwood

California’s signature wood, prized for outdoor use.

Resistance: Very high in heartwood. Comparable to or better than cedar.

Appearance: Deep reddish-brown, distinctive color. Tight, even grain.

Workability: Easy to work. Takes finish beautifully.

Availability: Limited and expensive outside California. Mostly from sustainable plantations now.

Best uses: Premium decking, outdoor furniture, hot tub surrounds.

Clear all-heart redwood is the premium grade—all heartwood, no knots. It’s expensive but exceptional.

White Oak

The only commonly available oak suitable for outdoor use.

Resistance: High. The same properties that make tight barrels make rot-resistant outdoor projects.

Appearance: Tan to light brown. Prominent grain. Ray flecks when quartersawn.

Workability: Moderate. Dense and hard. Dulls tools faster than softwoods.

Special property: Tyloses block the wood’s pores, making white oak waterproof. Red oak lacks this—water passes straight through.

Best uses: Boat building, outdoor furniture, wine barrels, gates, anything needing strength and durability.

White oak is heavy and expensive but extraordinarily durable. It’s overkill for many projects but perfect when you need wood that will outlast you.

Black Locust

The most rot-resistant wood native to North America.

Resistance: Exceptional. Fence posts last 50+ years in ground contact.

Appearance: Greenish-yellow to brown heartwood. Darkens with age.

Workability: Very hard. Difficult to nail without pre-drilling. Dulls tools quickly.

Availability: Not commercially common. Often sourced locally from woodlots.

Best uses: Fence posts, landscape timbers, ground-contact applications.

Black locust was the traditional fence post wood in eastern North America. It’s largely been replaced by treated lumber but remains superior where available.

Teak

The gold standard for marine and outdoor applications.

Resistance: Exceptional. Natural oils repel water and resist decay.

Appearance: Golden-brown with dark streaks. Weathers to silver.

Workability: Easy to work despite density. The oils lubricate tools.

Cost: Very expensive. The most costly commonly used outdoor wood.

Best uses: Boat decks, high-end outdoor furniture, applications where cost is secondary to performance.

Genuine teak comes from Southeast Asia. Its availability has decreased as old-growth forests disappear. “Plantation teak” is younger, less oily, and less durable than old-growth.

Ipe (Brazilian Walnut)

A South American hardwood increasingly used for decking.

Resistance: Exceptional. Outlasts most other decking materials.

Appearance: Dark brown with some grain variation.

Workability: Extremely hard. Requires pre-drilling for fasteners. Carbide tools recommended.

Density: Sinks in water. One of the heaviest commercial woods.

Best uses: Commercial decking, boardwalks, high-end residential decks.

Ipe is nearly indestructible but demanding to work. The dust is a respiratory irritant. It’s a premium material for permanent installations.

Cypress

The traditional outdoor wood of the American South.

Resistance: High in old-growth heartwood. Second-growth is less resistant.

Appearance: Light tan to yellowish-brown. Fine, even grain.

Workability: Easy. Similar to cedar.

Availability: Primarily in the Southeast. Less common elsewhere.

Best uses: Siding, decking, outdoor construction in its native range.

Old-growth “sinker cypress” salvaged from swamp bottoms is prized but rare and expensive.

Pressure-Treated Lumber

When naturally resistant species are unavailable or too expensive, treated lumber fills the gap.

How It Works

Wood is placed in a pressure vessel. Vacuum removes air from cells. Preservative solution is forced in under pressure. The treatment penetrates deep into the wood.

Modern Preservatives

ACQ (Alkaline Copper Quaternary): Copper-based. The green tint fades over time. Corrodes regular steel fasteners—use stainless or compatible hardware.

CA (Copper Azole): Similar to ACQ. Slightly different chemistry.

MCQ (Micronized Copper Quaternary): Copper particles suspended in solution rather than dissolved.

Older CCA (Chromated Copper Arsenate) is no longer used for residential applications due to arsenic content.

Limitations

Only sapwood treats effectively. Heartwood doesn’t absorb preservative well. A treated board with visible heartwood has untreated wood at the surface.

Treatment doesn’t improve strength. Treated wood is still pine (usually Southern Yellow Pine). It’s no stronger than untreated SYP.

Surface checking occurs. Treated wood cracks as it dries after treatment. This is normal but not attractive.

Finish compatibility varies. Wait for treated wood to dry before finishing. Freshly treated wood won’t accept stain or paint.

Best for: Ground contact, structural applications, anywhere appearance is secondary to durability.

Choosing for Specific Projects

Decks

Premium: Ipe, teak, clear redwood Mid-range: Western red cedar, white oak Budget: Pressure-treated pine

Decks get heavy wear—foot traffic, furniture, weather. Higher-quality materials last longer and look better but cost more upfront.

Fences

Posts: Pressure-treated or black locust (ground contact) Pickets: Cedar or pressure-treated Rails: Cedar or pressure-treated

Posts matter most—they’re in ground contact. Pickets and rails can use less resistant materials since they’re above ground.

Raised Garden Beds

Natural choice: Cedar (untreated—no chemicals near food) Alternative: Black locust, redwood, white oak Avoid: Pressure-treated (chemicals may leach into soil)

Food gardens are one place where natural resistance matters more than cost savings from treated lumber.

Outdoor Furniture

Premium: Teak, white oak Good: Cedar, cypress Okay if maintained: Many hardwoods with proper finishing

Furniture gets less weather exposure than decks (often under cover, moved indoors in winter) but must look good up close.

Planters

Best: Rot-resistant species or pressure-treated with plastic liner Note: Soil contact accelerates decay regardless of species

Extending Wood Life Outdoors

Regardless of species:

Keep wood off the ground where possible. Ground contact dramatically shortens life.

Allow water to drain. End grain absorbs water fastest. Design joints and connections so water doesn’t pool.

Apply finish. UV protection prevents graying and cracking. Water repellency reduces swelling and shrinking.

Maintain regularly. Annual cleaning and refinishing beats replacement.

Use appropriate fasteners. Stainless steel or coated fasteners prevent staining and rust.

Wood outdoors will eventually fail. The question is whether that’s in 5 years or 50. Species selection and maintenance determine the answer.

The Tree Identifier app helps you recognize trees that provide durable wood—the cedars, oaks, and locusts of the forest. Knowing what you’re looking at connects living trees to finished projects.