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How to build raised garden beds on concrete base?

I'm wanting to build a two tiered raised garden bed - first layer will be low for grass and then the second layer higher for garden beds. Looking at 2 x rectangle spaces approx. 2m long x 1m wide. First tier would be 300 mm tall (to allow for drainage, soil and turf) and then the second tier i'm thinking 600mm tall. all 4 sides would need to be built up to retain the soil.

My courtyard is currently all concrete and has a slight slope to the rear where there is an open drain that runs along the 4 townhouses.

I'm tossing up between concrete sleepers or blocks at the moment and wondering which will be easier for DIY installation? Especially since I need to do corners and any supporting brackets need to be attached to concrete.

Any guidance would be greatly appreciated!

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Comments

Jason

Hi @Nixxiola,

Welcome to Bunnings Workshop. It's great to have you join the community. Don't hesitate to post anytime you need a hand or have a project to share with other members.

It sounds like you have a solid idea of what you'd like to build. Do you have a sketch of the design as yet that you could share? It might help members better envisage what you're planning and help them to provide more specific and helpful advice.

Our resident Bunnings D.I.Y. expert @EricL has been trying to help as many people as quickly as possible during this busy time for D.I.Y. projects and will be happy to get back to you as soon as possible. Let me also tag some other experienced members who might like to join in the discussion and share their thoughts on your raised garden bed plans: @Adam_W, @diy_hausdesigns, @TheSaltyreefer, @Neo19 and @LePallet.

Looking forward to seeing your project come together.

Jason

Nixxiola

https://www.workshop.bunnings.com.au/discussion/comment/32865#Comment_32865

this is the closest I can find as to what I’m after!

Jewelleryrescue

Hi @Nixxiola

Nice planter design you picked.

And the project isnt too hard to build.

Can I ask is there an existing slab your building on if so you can build a freestanding planter box that sits on the concrete with some weed mat at the base to drain water but hold the soil in.

Or You can build a free standing planter and have star pegs hold it in place over a dirt or grass area with the same weed mat base .

From the photo you showed us the front height is approx 200mm (1 Treated pine sleep height) tall and the rear 400mm (2 treated pine sleeper heights) tall.

Paslode 150 x 5.6mm 500g Bullet Head Galvanised Nails - 13 Pack I/N: 2360507 $9.85

200 x 75mm 3.0m Treated Pine Sleeper CCA H4 I/N: 8032712 $43.55

so I would recommend you use the sleepers supplied size length ways 3 metres (you can cut it or buy other sizes too.)

Simply make a box for level 1 sittng on the ground Rectangle or square or more than one length joined together, the side pieces nailed at the ends. Then make the smaller box two and sit it on top of box one only half the width of box 1 to produce the teir effect. cut inside timber 45 by 90mm treated pine posts for the sleepers to screw or nail into and it alings and supports second box section.

A more advance version can be view here but it dosnt have to be as involved your fisrt build.

https://www.workshop.bunnings.com.au/t5/How-To/How-to-build-a-raised-garden-bed/ba-p/29674

EricL

https://www.workshop.bunnings.com.au/discussion/comment/78777#Comment_78777

Hello @Nixxiola

My apologies for the late reply. It's great that you've received excellent advice from @Jewelleryrescue. Just to add to the suggestions made, I came across a discussion which I suggest having a look at - Tennis court vegetable garden featuring raised beds by @martincopland. This is an excellent example of how to build a raised garden bed using Sienna or ACQ treated sleepers with a concrete floor. This configuration can also be built using concrete sleepers.

Between the two it's easier to drill into timber, but you can drill into the concrete sleepers as well it will just take a little bit more effort. The assembly is kept together using Ridgi Galvanised Steel Corner Post Upright Sleeper or you can use timber posts to build the box assembly. Drainage is address with weed matting and erosion control matting at the bottom.

I suggest having a good look at the material sizes to give you a good idea of the height you can build your garden bed to. For example, the Ridgi 1.5m x 150 x 50mm Smooth Grey Concrete Reinforced Sleeper is only 150mm tall which means that you'll need two of them to reach 300mm. The 200 x 50mm 2.4m Sleeper Hardwood - 50mm is 200mm tall and when doubled will give you a garden bed that is 400mm tall. Just keep this in mind when planning your garden bed.

I propose visiting your local store and having a look at the materials available. This will give you a much better idea of what you can use for your garden bed. I then suggest drawing up a plan on paper. This will quantify the parts that you'll need such as the number of timber pieces you'll be needing, how many screws and the quantity of weed matting to cover the inside of the raised garden bed.

If you have any other questions we can help with, please let us know.

Eric

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