How to build brick garden bed?

Hi guys, i have a question regarding my backyard. I am doing a DIY landscaping of my backyard, I want to put a garden bed made of adbri masonry blocks 800mm wide and 600mm high. My question is, can I use my old bricks to cover the timber sleepers under the existing fence? Then a timber retaining wall painted with bitumen in front of it before i put the blocks to comblete the garden bed of course after creating a footing. Also, do i need to put a drain? The garden bed will be along the fence. Thanks for your advice.

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Comments

JacobZ

Hi @jehpets,

Thank you for your questions about your D.I.Y. landscaping project.

I can't see any reason you couldn't use the old bricks to cover the sleepers beneath your fence. Was there a particular reason that you ask? Is there something about this application that concerns you?

Just make sure the bricks aren’t directly trapping moisture against the timber — a small gap or drainage path between them helps prevent rot over time.

Painting the timber retaining wall with bitumen is also a smart move, as it adds a waterproof barrier to help protect the wood from soil moisture once the garden bed is in place.

Since the bed will be 600mm high, yes, a drain is strongly recommended, especially because it’s located along a fence. You can install a perforated agi pipe at the base of the wall, surrounded by gravel, and direct it to a suitable drainage point, preferably a stormwater outlet. This will prevent water from pooling behind the wall, which can cause pressure buildup and potentially damage the structure or fence over time.

In summary: yes, reuse your old bricks if they’re sound, bitumen-paint the timber, and definitely include proper drainage. With those steps covered, your garden bed will be stable, long-lasting, and ready for planting.

Let me know if you have any further questions or concerns.

Jacob

jehpets

https://www.workshop.bunnings.com.au/discussion/comment/58532#Comment_58532

Thanks Jacob! What height should the garden bed be so that I don't have to put a drain? Thanks. The stormwater drain is quite far from this area.

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/91638#Comment_91638

There's no specific height @jehpets. Any garden bed needs some drainage. How are you going to be bedding the blockwork with the footing? If the bottom of the garden bed is open and on the soil, then you don't necessarily need drainage, as water will flow through it and seep into the soil below. However, during torrential downpours, it can fill with water, which is why a drain is recommended.

If the stormwater outlet is too far away, you can add some ports or drainage holes around the bottom course of blocks to let the water escape into the area surrounding the bed.