Hi @twochicks,
How wide do you want your seat to be?
I imagine you'll want it to be roughly the same width as your table, which will affect the design. Decking boards are designed to span no more than about 600mm unsupported, so if your bench seat was so wide that the gap between the legs was more than this, then you'd need to either add a third leg or consider moving the legs in from the ends.
I think the Rapid Steel Tube Leon Bench Legs would be a solid and aesthetically pleasing option for your outdoor benches. With the predrilled holes, this makes construction very simple, just requiring you to drive screws up through them into the underside of the timber to lock the boards in place.
Being 300mm wide, they would be the perfect size to fit two of your 150mm merbau decking boards side by side, although I would recommend leaving a 3-5mm gap between the boards to allow water to drain and for slight expansion and contraction of the boards.
How thick are your decking boards?
We would need to find a 12g screw that can go through the top of the furniture legs, which are 4mm thick, and into the decking boards without poking out the top.
When we have a suitable screw, assembly would just mean driving the screw up through the legs into the decking boards to lock them in place.
If your merbau has not already been oiled, you would just need to apply two thin coats of decking oil to help protect them from the elements.
Let me know what you think and if there is anything that requires clarification, please let me know so I can assist further.
Jacob
