Honestly, the short answer is yes – you can absolutely bolt street benches to wooden decking, not just concrete. But the real answer is that how you do it makes all the difference between a bench that feels rock-solid for years and one that starts wobbling dangerously within a few weeks. I’ve helped friends install a few of these on timber decks, and here’s what I’ve learned through trial and error.
First off, concrete is the simpler case. You drill holes, use expanding anchor bolts or concrete screws, and the mass and rigidity of the slab do all the hard work. A wooden deck is a completely different animal. Even if your deck feels stiff when you walk on it, sitting a heavy cast-iron or steel bench with multiple people on it introduces forces that can loosen ordinary screws or crack deck boards.
The critical question is what’s underneath those deck boards. If your decking is just thin boards nailed to a flimsy subframe, bolting straight through the board alone is a recipe for disaster. The bench will eventually rip the boards up. You need to transfer the load into the structural joists. The ideal method is to locate the deck joists and use structural timber screws or coach bolts that pass right through the deck board and deep into the center of a joist. Stainless steel coach bolts with wide washers and nylon lock nuts are my go-to for this – they won’t rust, won’t vibrate loose, and spread the load beautifully. If the bench leg doesn’t land directly over a joist, you may need to add bridging timber between joists, secured with joist hangers, to create a solid fixing point under the deck surface. Don’t just rely on deck screws into the board; that’s for holding down a light planter, not a public-style bench.
Another thing people forget is timber movement. Wood expands and shrinks with the seasons. If you bolt too rigidly without allowing for a tiny bit of slip, you might encourage splits around the holes. I like to slightly oversize the hole through the deck board and use a protective bit of rubber or a nylon sleeve between the bolt and the timber, then tighten down onto a large metal plate underneath so the bench clamps the structure together without strangling the wood fibers.
So, concrete or decking – both work, but decking demands more planning. Check the bench’s base dimensions against your joist layout before buying. If the bench is light aluminum, you might get away with heavy-duty deck screws into joists, but I’d still sleep better with through-bolts. And always, always check the load-bearing capacity of your deck first. An old deck with some rotten joists won’t safely hold a heavy street bench no matter how many bolts you throw at it. In short: yes, you can do it, and do it well – just treat the deck’s structure with the respect concrete doesn’t even ask for.