How to build garden bed against Hebel?

Question

Good afternoon.

I am wanting to build a raised garden bed at the front of my house.

The back of the garden bed will butt against our hebel wall with the front and sides being made of brick.

Do I need to do something particular against the hebel or can I just build the front and sides and fill with soil

MitchellMc · Answer

Hi @GavandKaty,

You’ve already had some helpful input from Eric, but I’d just like to expand on one important point, because this is one of those situations where a small design decision can have long-term consequences for your home.

Using your Hebel wall as the back wall of a raised garden bed (even with a waterproofing membrane applied) isn’t something that's generally recommended. You are essentially overriding your dampcourse layer in the wall, which is there to prevent rising damp and water penetration into the wall. Typically, we don't even recommend building a garden bed against a foundation, let alone a raised garden bed against a home's wall.

While membranes can provide protection, they’re not a fail-safe solution in this kind of application. Over time, things like soil movement, roots, fixings, or minor installation damage can compromise the membrane. Once that happens, moisture can track into the Hebel and potentially affect internal finishes or framing. Hebel is particularly important to protect because it’s more porous than traditional masonry.

Best practice options would be:

* Build a fully independent garden bed (front, sides and rear wall), rather than relying on the house wall as part of the structure.
* Leave a gap between the bed and the Hebel wall. Even 50–100mm is enough to allow airflow and prevent moisture build-up or wicking.
* Ensure the base has good drainage (gravel layer + free-draining soil mix) so water isn’t sitting against any structure.

But again, the safest and most durable approach is to keep the garden bed structurally independent and slightly separated from the house.

It might seem like a small detail now, but it can save a lot of headaches down the track.

Please let us know if you have any questions.

Mitchell

EricL · Answer

Hello @GavandKaty

Thank you for sharing your question about installing a raised garden bed in front of your house. I propose using

https://www.bunnings.com.au/gripset-betta-1l-waterproofing-membrane-bitumen-rubber_p0960165

on your Hebel and brick wall. This will prevent moisture from penetrating the wall and travelling through the other side causing paint damage to your interior wall.

However, if you decide to use sleepers to build your garden bed, I recommend building it as an independent structure away from your house wall. I suggest a distance of at least 100mm. This will guarantee that there will be no soil contact and moisture exposure.

I recommend having a look at these guides:

* How to build a raised garden bed by @Adam_W 
* How to build a simple raised garden bed by @Adam_W

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

Eric