I want to create a garden bed close to the home. What protective membrane could I use to protect the home from moisture and will I need to install an agi pipe underneath the garden bed. I plan to plant hydrangeas.
Hi @pauly85,
It’s best not to build garden beds directly against your house wall or rely on the wall itself to retain the soil, even if you plan to install a waterproof membrane. While membranes and waterproofing products can help reduce moisture transfer, they can still become damaged over time from soil pressure, movement, roots or accidental punctures. If the waterproofing fails, moisture can become trapped against the wall and lead to issues such as dampness, staining or even structural damage over time.
A much better approach would be to build a self-contained raised garden bed slightly away from the wall using sleepers, blocks or another retaining material. This creates a protective barrier that takes the weight of the soil and helps keep moisture away from the home.
Check out https://www.bunnings.com.au/diy-advice/garden/planting-and-growing/how-to-build-a-raised-garden-bed-with-sleepers for some guidance on how to build a basic garden bed using sleepers.
Installing agi pipe beneath your raised garden bed can also be worthwhile, particularly if the area tends to stay wet or if the bed will be heavily irrigated for hydrangeas. Considering the proximity to your home's foundation slab, it would certainly be worthwhile to ensure excess water is moved on. I note that you have downpipes nearby that are hooked into underground stormwater pipes. Agi pipe needs to have a drainage point, and a stormwater pipe is usually the best option. In saying this, any connection to a stormwater pipe needs to be carried out by a licenced plumber, so if you plan to do this, you'll have to factor this into the plan.
Please let us know if you can upload a few photos of the area or some dimensions, as that would help members suggest the best garden bed design for your space.
Jacob
