You know, I get this question a lot from folks planning to install benches in parks, gardens, or even along busy walkways. And honestly, the answer isn't a simple "wood wins" or "metal lasts forever." It really depends on what kind of abuse they're going to face and how much care you're willing to put in.
Let's talk about wooden slats first. Most park benches use pressure-treated pine, cedar, or teak. Cedar and teak are naturally oily and rot-resistant, so they can pull through 10 to 15 years in a decent climate. But here's the catch: wood is vulnerable to moisture and sun. If you skip sealing them every couple of years, that pretty grain starts cracking, splintering, and eventually rotting at the joints. I've seen a beautiful teak bench turn into a rough, splintery hazard after just three wet winters without a coat of protective oil. So, wood demands regular TLC.
Now, metal slats—usually powder-coated steel or aluminum. These are tough nuts. A well-coated steel bench can easily outlast a wooden one by a decade or two if the coating stays intact. The big enemy here is scratching. Once that powder coating chips—maybe from a dropped bike or a dragged piece of furniture—moisture seeps in and rust blooms. It's not splintery like wood, but rust stains are ugly and can weaken the structure over time. Aluminum benches? They don't rust, but they can bend under heavy misuse and feel icy cold in winter and scorching hot in summer.
In a head-to-head durability test, I'd say metal slats often win on pure lifespan if you don't mind the occasional touch-up with rust-resistant paint. But for comfort and natural aesthetics, wood is the winner. However, that comfort comes with a promise of annual maintenance. So, if your bench sits in a coastal area with salty air, go with aluminum or properly sealed teak. If it's in a dry, covered spot, wood will serve you beautifully for years with minimal fuss.
Really, the best choice comes down to your local weather and your willingness to grab a brush and a sealant every spring. Both materials are durable in their own ways, but neither is indestructible.