Ask what wood belongs outside and you'll get one of two answers: teak, or iroko. They solve the same problem the same way — defense built into the board itself rather than painted on top — which is exactly why choosing between them confuses people. The differences are real, but they aren't the ones most buyers expect.
What they share
Both are dense tropical hardwoods whose heartwood carries natural oils that repel water and resist rot without any coating's help. Both stay dimensionally calm through weather swings and both shrug off insects. At Formhaus, iroko is the stocked exterior species; teak we source by custom order. Left outside untreated, both weather the same way: the surface turns a uniform silver-grey while the board underneath stays sound. On pure survival, this contest is close to a tie — which means the decision actually turns on look, feel, and money.
The case for Teak
Teak is the benchmark every outdoor wood is measured against, and it earned that standing at sea — ship decks, boat rails, and estate furniture have run on it for centuries. The board is loaded with oils and natural silica, its color is an even golden brown, and its grain runs mostly straight and quiet, so a teak top reads calm and uniform across a whole run of pieces. It also carries the weight of its own name: when a designer or client specs teak, everyone at the table knows exactly what's arriving. That pedigree is priced in — and at Formhaus it's a custom-order board, quoted per project.
The case for Iroko
Iroko is a West African hardwood that's been called African teak for over a century, and the nickname is deserved where it counts: the same natural decay resistance, the same stability, the same ease in the weather. It's actually the harder board of the two — about 1,260 on the Janka scale to teak's 1,070 — so it takes daily knocks slightly better. Fresh boards run yellow-gold and deepen toward a rich amber-brown as they see light, and the interlocked grain shows more movement and character than teak's straight lines. The deciding virtue is cost: iroko delivers most of what teak is prized for at a fraction of the board price, which is why a patio's worth of restaurant tables usually pencils out in iroko.
The honest differences
Appearance: teak is uniform and reserved; iroko has more figure and more color variation board to board — some buyers call that character, others call it busy. Color over time: iroko's shift from gold to brown in its first months of light is more noticeable than teak's gentle mellowing. Hardness: iroko by a nose, though neither species fails outdoors on hardness. Cost: not close — this is the real separator. Availability: iroko is on the rack and prices live; teak quotes as a custom order. Everything else people claim separates them mostly doesn't survive contact with the boards.
How both age — and the choice that matters more
Whichever species you pick, the bigger decision is the weathering plan. Leave the piece untreated and it silvers evenly to that driftwood grey many owners deliberately want. Keep it oiled on a schedule — once or twice a season, more in hard sun — and it holds the color it arrived with. Neither answer is wrong, but it should be made before delivery, because many owners order outdoor pieces Unfinished and run the exterior oil themselves from day one. Tell us the piece lives outside when you order and the shop will confirm the finish path with your spec.
The decision in one paragraph
Spec teak when the project calls for the benchmark — the uniform golden look, the marine pedigree, or a client who asked for it by name. Spec iroko when the quantity math matters, which in practice is most patio fleets and production runs; you give up almost nothing that shows up outdoors. The making — milling, glue-up, joinery — prices identically for both, so the board alone moves the number. Price the piece in Iroko in the configurator; if teak is still calling, send the same spec through the custom path and let the two quotes argue it out. And if the eye has a vote, order the iroko sample and put the real board in the real light.