If you need a lightweight outdoor bench for a rooftop garden, go with powder-coated aluminum. I’d choose it over wood, steel, or plastic because it gives you the best mix of easy handling and weather resistance. Aluminum is light enough to carry up stairs and shift around when you rearrange planters, but a well-built frame still feels stable. The powder coating protects the metal from rain, salt air, and UV, so you won’t deal with rust or peeling the way you might with steel or cheap resin.
Teak and acacia are beautiful, but solid wood is heavier than it looks and needs regular sealing on a hot, exposed rooftop. HDPE or poly lumber is the best runner-up: it’s weatherproof and low-maintenance, but it tends to be heavier than aluminum and can get very warm in direct sun. Wrought iron and steel are too heavy for most rooftop setups and can rust once the finish gets scratched.
One rooftop-specific trick: even a lightweight bench can slide in strong wind. Pick a lower, slightly wider silhouette, place it against a wall or railing, and use furniture anchors or sandbags if your rooftop gets gusty. For cushions, quick-dry foam with UV-resistant fabric will save you from hauling them inside after every rain.
So for a rooftop garden bench, powder-coated aluminum is the best material. It’s light, rust-resistant, low-maintenance, and looks clean against planters and skyline views.