Great question! When I’ve looked into this myself, I found that most outdoor benches—especially those you buy from home improvement stores or online retailers—are actually assembled with screws. Nails are much less common for these kinds of projects, and here’s why.
Screws offer superior grip and hold, which is important for a piece of furniture that will face rain, sun, wind, and even heavy sitting weight. Over time, nails tend to loosen up because wood expands and contracts with moisture changes. Screws, on the other hand, bite into the wood tightly and stay put. Plus, if you ever need to disassemble the bench for storage or moving, screws make it easy to take apart and reassemble without damaging the wood.
That said, you might occasionally see an outdoor bench assembled with nails if it’s a very cheap, low-end model or a rustic DIY build. Some traditional craftsmen also use galvanized or stainless steel nails for aesthetic reasons, but even then, screws are the stronger, more reliable choice for most users.
In short: Unless it’s a vintage or intentionally rustic piece, your outdoor bench likely used screws. If you’re building your own, go with exterior-grade screws (like stainless steel or coated deck screws) to prevent rust. Trust me, your backside and your bench will thank you later.