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The short answer: black locust and white oak are the most rot-resistant woods you can realistically buy in North America, and western red cedar is the best compromise between decay resistance, weight, and price for most garage-shop builds. The trade-off is straightforward — the denser and more decay-proof the species, the heavier, harder to machine, and more expensive it gets. Teak sits at the top of the durability chart but at a price that rarely makes sense for a first outdoor project.
Rot resistance in wood comes from extractives — the same compounds that give heartwood its color. Those extractives fade from the sapwood to almost nothing, so every recommendation below assumes you are buying all-heart stock. A cedar board with a wide band of pale sapwood on one edge will rot at that edge years before the rest of the piece fails.
How wood decay ratings actually work
The USDA Forest Service rates heartwood decay resistance in four broad classes: very resistant, resistant, moderately resistant, and slightly or non-resistant. The ratings apply to ground-contact exposure, which is the harshest condition. Furniture on a deck or patio is above ground and dries out between rain events, so a “resistant” species performs considerably better in a chair leg than in a fence post.
Two practical caveats. First, these ratings describe untreated heartwood; any finish, oil, or paint you apply extends life further by slowing moisture cycling. Second, resistance is not the same as stability. A rot-proof wood that cups and splits every season will open joints and let water in, and that water does more damage than the species choice ever saved you.
Species-by-species comparison
The table below uses conservative, commonly published figures. Board-foot prices are rough retail ranges for clear or near-clear stock at a hardwood dealer; big-box cedar and cypress run cheaper but with more defects. Janka hardness is given because it predicts how the wood behaves under a chisel and a router bit.
| Species | Decay resistance (heartwood) | Janka hardness (lbf) | Weight (lb/bf, air-dry) | Typical price ($/bf) | Best use |
|---|---|---|---|---|---|
| Black locust | Very resistant | ~1,700 | ~4.0 | $4–$8 | Legs, ground-adjacent frames |
| White oak | Very resistant | ~1,360 | ~3.8 | $7–$14 | Structural frames, arms, slats |
| Teak | Very resistant | ~1,070–1,150 | ~3.5 | $25–$45 | Tabletops, exposed details |
| Western red cedar | Resistant to very resistant | ~350 | ~1.9 | $3–$7 | Backs, seats, anything overhead |
| Bald cypress | Resistant | ~460 | ~2.3 | $5–$9 | Seats, panels, painted work |
| Black walnut | Very resistant | ~1,010 | ~3.3 | $9–$16 | Accent pieces where looks matter |
| Redwood (old-growth heart) | Resistant | ~420 | ~2.2 | $8–$18 | Seats, back slats |
A caveat on redwood and cypress: most of what reaches a retail yard today is second-growth with a high proportion of sapwood, and the decay resistance of that material is a fraction of what the old-growth reputation implies. Ask for heart content and look at the end grain before you commit.
Matching species to the part of the furniture
You do not need one wood for the whole piece. A bench built with black locust or white oak legs and cedar back slats costs less and weighs considerably less than an all-oak version, and the parts that touch wet ground get the species that handles it. This is the same logic as picking species by how they cut — see our comparison of wood species for hand-cut joinery for the machining side of the decision.
Where the wood matters most:
- Legs and feet: white oak or black locust. Feet sit in splash and standing water; density here buys years.
- Seats and backs: cedar, cypress, or redwood. Light, stable, and easy to shape with a spokeshave.
- Tabletops: white oak if you want to leave it bare, teak if the budget allows. Both resist cupping better than cedar in wide panels.
- Arms and stretchers: white oak. Long thin members need stiffness, and cedar is too soft for the loads.
If your shop is tight, species choice interacts with how you assemble the piece. Our guide to choosing joinery for a small garage shop covers which joints you can cut without a full-size bench.
Density, machining, and the chisel problem
White oak and black locust are hard enough that joinery takes real effort. Expect to sharpen more often, especially when chopping mortises. A 1-inch mortise in white oak will dull an edge noticeably faster than the same cut in cedar, and if your sharpening setup is marginal you will feel it by the fourth leg. Budget for a decent sharpening station — our cost breakdown for a sharpening station gives realistic numbers.
White oak has one machining quirk worth knowing before you start: it is ring-porous, and the pores are open enough that water can move through end grain and along the grain through exposed end faces. That is why white oak barrel staves work — the wood swells and seals. For furniture, it means end grain should get finish, and joints should be glued, not just pinned. Black locust, by contrast, cuts more like hickory: hard, slightly brittle, and prone to tearout around knots.
What goes wrong, and the most common mistake
The single most common mistake in outdoor furniture is using an exterior-rated wood and then trapping water against it. People buy expensive white oak, cut tight mortise-and-tenon joints with no drainage, glue the whole thing shut, and set it on a concrete patio where the feet stand in puddles. The wood outlasts the design by maybe one season.
Three fixes, in order of impact:
- Lift the feet off the surface. Add 1/4-inch to 3/8-inch polymer or stainless glides, or shape a slight chamfer on the bottom of each leg. Standing water is what kills outdoor furniture, not rain.
- Leave a path for water. Do not glue tenons that will sit in a horizontal rail. Pin them, or use a joint that drains. Slats should have 1/8-inch to 3/16-inch gaps.
- Finish all six faces. The underside of a tabletop or the inside of an apron gets the same coating as the top. Unfinished faces absorb moisture at a different rate and drive cupping.
Second most common: buying “cedar” at a big-box store and getting aromatic cedar (eastern redcedar) fencing stock, which is a different species with lower decay resistance and a lot of sapwood. Western red cedar is what you want.
Fasteners and finish by species
White oak and black locust are acidic and corrosive to plain steel. Use stainless steel or hot-dip galvanized fasteners — not electro-galvanized, and not exterior deck screws with a thin coating. Cedar and cypress are less aggressive but will still stain from cheap screws over a few seasons.
On finish: a penetrating oil (tung oil or a deck oil with a UV package) suits cedar and cypress because it moves with the wood and is easy to refresh annually. White oak and teak can be left bare to weather to gray, or oiled if you want to keep the color. Film finishes like polyurethane crack on outdoor furniture within a couple of seasons and then trap water under the flaking film, which is worse than no finish at all.
Decision checklist
- Confirm the stock is all heartwood — check the end grain for pale sapwood bands.
- Choose white oak or black locust for any part within 6 inches of the ground.
- Choose cedar or cypress for seats, backs, and any part you want to keep light.
- Set a budget per board foot before you go to the yard; white oak at $10/bf triples the material cost of a cedar bench.
- Plan drainage into the design: glides on the feet, gaps between slats, no glue in horizontal tenons.
- Buy stainless or hot-dip galvanized fasteners sized for the species.
- Finish every face, including the ones nobody sees.
- Skip teak unless the piece is a display object — the cost per board foot rarely pays back on a bench.
Frequently asked questions
Is pressure-treated lumber a good choice for outdoor furniture?
It is rot-resistant and cheap, but modern residential-treated stock is intended for structural use and takes paint poorly until it has weathered a season. It also checks and splinters more than cedar. For a bench you will sit on, cedar or cypress is a better surface.
How long will a cedar bench last outdoors?
Untreated western red cedar heartwood in above-ground furniture typically gives 15 to 20 years with annual oiling, and somewhat less if left bare and sitting in wet conditions. White oak and black locust generally outlast it, at roughly double the material cost.
Can I mix species in one piece of outdoor furniture?
Yes, and it is often the smart move. Use a dense, very resistant wood for legs and feet, and a lighter species for seats and backs. Account for different movement rates by leaving slightly larger gaps at cross-grain joints.
Does white oak need to be sealed outdoors?
It does not need a film finish, and many builders leave it bare to weather gray. If you want to slow the graying and reduce surface checking, apply a penetrating oil once a year. Avoid polyurethane, which cracks and traps moisture.
How do I tell heartwood from sapwood at the lumber yard?
Look at the end grain: heartwood is darker and occupies the center, sapwood is pale and sits near the bark. On a fresh end cut the boundary is usually obvious. Ask the dealer for the heart content percentage if you are buying a large lot.