How to make outdoor bench seating for table?

[twochicks]

Hi all,

I'm planning to build two bench seats to pair with my outdoor table and would appreciate some design suggestions.

What I have:

• Several 150mm Merbau boards (leftover timber)
• Considering Rapid Steel tube coffee table legs as a potential frame option

What I need help with:

• Construction methods and joinery techniques suitable for outdoor use
• Alternative leg/frame options if the coffee table legs aren't ideal
• Whether I should treat or finish the Merbau in any particular way for outdoor durability

Has anyone tackled a similar project? I'd love to hear your recommendations on the best approach to assemble everything securely.

Thanks in advance, Nick

[JacobZ]

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

[twochicks]

Hey Jacob,

Thanks for the feedback. The boards are only 19 mm thick, and the width needs to be 2 meters. Prefer not to get a third leg or bring them in too much. Another option would be to look for a thicker board.  

Are the bench legs suitable for outside conditions?

Thanks, Nick 

[EricL]

Hello @twochicks 

The Rapid Steel Tube Leon Bench Leg 300 x 450 x 50mm BLK are powder coated which will provide a measure of defence against humid weather. The product description does not mention if it can be used outside exposed to full weather conditions. If the bench seating is under cover and not exposed to heavy rain the legs can be used outside. Because the board you've chosen is not so thick there is a possibility that the board will bow when too many people sit on the bench seat. My best advice is to consider installing a third leg in the middle to properly support the bench seat.

One other possible option is to create a timber frame to serve as the legs for the seat. 

Let me call on our experienced members @Dave-1, @Noyade and @Nailbag for their recommendations.

If you need further assistance, please let us know.

Eric

[J-P]

@twochicks - Pls try framing like I have done here. It is 1.8m bench for my dining table and is able to fit 3 adults with no bowing. https://www.workshop.bunnings.com.au/t5/Whole-of-House/How-to-build-a-bench-seat-for-a-dining-table/...