How to create Japanese dry garden on balcony?

Question

Hi all,

I'm entertaining the idea of putting a Japanese dry garden on my apartment balcony. This would primarily consist of a ~5cm bed of gravel, specifically 10mm Crushed Western White*. I intend to rake the garden weekly or so.

My balcony has a tiled floor and I assume a waterproof membrane beneath, so I would like to avoid any damage to it. It also has a drain in the middle and two gaps in the balustrade, see pic below ⤵️

I have a few questions:

* What measures would I need to take to support the gravel bed?* I did some googling and I've been suggested a layer of drainage cell + geotextile drainage mat, so that the gravel bed won't trap water against the tile and wear away the grout.
* What's the best way to join the drainage mat strips together? I assume there will be a lot of lateral movement (from walking over + raking the gravel)

* How should I go about blocking off the two wall gaps to stop gravel spilling off my balcony?
* Is there anything else I'm missing/I need to consider?

Thank you for taking the time to read this!

*I emailed Auburn Botanic Gardens to ask for the exact gravel they use for their own Japanese gardens.

Corns · Answer

Thank you for your advice @JacobZ and @Dave-1 . You are right that the weight, moisture and wear would be a major concern with this project. I'll have to think through it a lot more - thank you for the suggestions of alternative ideas as well.

Dave-1 · Answer

Good Evening @Corns

The loading of the floor would be what concerns me. As @JacobZ has mentioned it will add a substantial overall weight to the balcony. Im not sure what your balcony is rated at but getting it past strata laws and the engineering specs might push it out of the realm of doable.

I wonder if you could use other items that have a Japanese theme such as screens, plants that suit the theme but most importantly maybe a 1m square sand garden with an low edge.

- Im thinking of a base of Specright formply 1800 by 1200mm

- With a low 40 mm edge to contain the sand. The sand dosnt have to be deep, even around 20mm would work well.

- You could glue Tuscan path pebbles to the edge to hide the timber.

Dave

JacobZ · Answer

Hi @Corns,

Welcome to the Bunnings Workshop community, it is wonderful to have you with us.

Unfortunately, a balcony-wide gravel bed is not a good idea. A 50mm layer of gravel can add roughly 75 to 90kg per square metre, depending on the stone used. Once you include people, furniture, pots and any retained water, that becomes a significant extra load on a balcony and would bring strata/body corporate approval and a structural engineer into the conversation.

I’d also be very concerned about putting loose gravel down as it will almost certainly cause damage to the surface beneath regardless of efforts to stop that. Any movement from walking, raking or shifting gravel can abrade the tiles and damage the grout lines as well as any weak points around the edges or penetrations over time. The drain is another issue, as small stone fragments, dust, leaf litter and sediment can work their way through the gravel and matting and gradually block the outlet. Also, because the whole system would hold moisture underneath with limited airflow, it would also be very likely to become a mould and mildew trap, if any water were to blow in, which is pretty much inevitable.

It sounds like a lovely idea, but unfortunately, I don't think it is practical.

I’d suggest looking at lighter, contained options instead. Large pots, trough planters, bonsai, feature rocks, timber decking tiles, or a small, contained tray of gravel could still give you a Japanese garden feel without loading the balcony or risking damage to the waterproofing.

You might like to check out 8 ways to transform your balcony and

https://www.bunnings.com.au/diy-advice/home-improvement/design-inspiration/create-a-balcony-look-to-love

for some ideas.

https://www.workshop.bunnings.com.au/discussion/270124/8-ways-to-transform-your-balcony

Allow me to tag our helpful members @Nailbag, @Dave-1, @homeinmelbourne and @prettyliving to see if they have any ideas.

Jacob