How to build a concrete outdoor island bench?

[damianpc]

Hi. 

We are looking at building an outdoor island bench with a concrete top, poured in place. The island is not directly exposed to weather but could cop a bit, depending on the severity/angle of the weather. 

The bench will be roughly 2m L by 1m deep. Concrete top may overhang on the rear side. 

I have 2 questions:

-1) If built sturdy, will a timber frame support sufficiently a concrete top, about 3/4cm thick? As i'd prefer to build the frame from timber as opposed to brick. 

-2) We are wanting to clad in something like James Hardi stria panelling. What is the best method to prevent moisture getting inside to the frame? And what to build the frame from, to assist with this. Treated pine?

Thanks in advance. 

[Dave-1]

Morning @damianpc 

Nice sketch I dont see a problem with making that up yourself. Tho one suggestion I will make is that once made you put the concrete bags (un-used) on top of the frame work and then see fow solid it feels. Just a precaution and I would do the same with a frame I was building. I did it with my Bench seat Yeah threw myself at it and flopped at the points that wernt supported by wheels just to test it I figure if you can stress test it and it passes then its go ahead time. Just rem someone will also be sitting on the table several times over the lifespan of it BBQ's are BBQ's

Dave

[damianpc]

Thanks everyone for your very helpful advice. 

Another option I had considered was pouring the slab, maybe 200/300mm, and setting in the concrete post stirrup anchors, and using 90 x 90mm treated pine as the uprights.

Then using cross bracing between all uprights as well (without cross bracing)

See rough pic below, dotted lines of stirrups is what would be set within the concrete. 

 

[EricL]

Hello @damianpc 

That's definitely an option you can explore, but please make sure to have it certified by a draftsperson or engineer to make sure that it can carry the weight of the concrete benchtop.

If you need further assistance, please let us know.

Eric

[Dave-1]

Evening @damianpc 

Thats a solid support and the cross bracing will definently strenthen it. It may end up looking chunky. You could draw up a welded table and top and then go down to your light industrial area and see a welder/metal manufacturer would be able to weld it for you? I have those type of stirrups for my pool deck and they are solid as a rock with a lot of weight above. They are cross braced as well. The difference between the deck and the table is you dont see the feet of the deck

Dave

[damianpc]

Thanks for that. Good thing is I'm going to clad the whole face with hardi groove or similar. So you shouldn't see the inside. 

With your stirrups were they set in the concrete or bolted in afterwards. I'm potentially looking at bolting in once the concrete is set, maybe using chemical anchors. 

Cheers

[Dave-1]

I set the stirrups in the concrete and then adjusted the heights of the posts acordingly. The ground slopes so there were a few things to factor in for me.

Pool deck stage 1 step 2 will show you how I concreted the posts in. The holes were 500odd mm deep from memory.

Bolting to a slab would work as well and then you could remove if wanted to a lot easier. 

Dave