Do I need retaining walls before my new house build?

Often yes on sloping blocks. Retaining creates a level, compact platform, protects the slab area from soil collapse, and allows services and fencing to be staged cleanly.

Do I need council approval or engineering?

In SA, walls over 1 m typically need council approval and an engineer’s design. Extra rules can apply near boundaries, easements, steep slopes, or when wall+fence exceeds 2.1 m.

Which retaining wall type is best for new builds?

Concrete sleepers (plain or stone-textured) and masonry/block systems are durable and low-maintenance. Stone, brick, gabion, and timber can suit specific design and budget needs.

Can fencing sit on top of the retaining wall?

Yes, commonly for space and cost efficiency. The wall and fence must be designed together to meet structural and height rules; approvals may apply.

What drainage should a retaining wall include?

Granular backfill, geotextile separation, and weep holes or pipework to relieve hydrostatic pressure and prevent water discharge onto neighbouring properties.

When should retaining be built in the construction sequence?

After survey, design, and approvals, build the wall and drainage before the slab. Then complete fencing/services and proceed to house construction.

Before You Build: Retaining Walls for Sloping Blocks in Adelaide

Joseph B.
Oct 9, 2024
2 min read

Planning a new home on a sloping block? Before the slab goes down, make sure your site is properly cut, retained, and drained. Building on level, compact, stable ground protects your foundations, prevents soil collapse, and keeps your construction timeline on track.

Why Retaining Walls Matter Before a New Build

Create a level platform: Cuts and excavations often need retaining to hold back soil safely.
Protect the build zone: Prevents soil from slumping into your pad or access areas.
Control stormwater: Correct drainage behind walls stops hydrostatic pressure and damage.
Stage the site: In some cases, walls should be built before the house so fencing, services, and neighbour works can proceed cleanly.

Boundary Retaining Walls & Fencing on Retaining Walls Sloping Block

Retaining walls may be required on or near boundaries to keep different ground levels stable on both properties. Often, neighbours choose to mount fencing on top of the retaining wall to save space and cost. If a neighbour is ready to build first, you might still install the wall now so both parties can progress without delays.

Not sure about approvals or setbacks? Square Gardens can coordinate engineering, council applications, and survey so your boundary wall is compliant from day one.

Choose the Right Wall Type for Your Block

Your site conditions (soil, level change, access) and look/maintenance preferences guide the best choice:

Concrete sleeper retaining walls (plain or stone-textured)Steel-reinforced, ultra-durable (low maintenance), ideal for new builds and long straight runs. Excellent strength-to-footprint ratio.
Masonry/block retaining wallsEngineered systems with a premium architectural look. Highly stable and long-lasting.
Natural stone (e.g., sandstone)Timeless aesthetics built by a skilled stonemason; perfect for feature areas and premium streetscapes.
Brick retaining wallsClassic or rendered modern finishes; requires correct drainage and reinforcing details.
Gabion retaining wallsRock-filled cages—robust, permeable, and visually striking for contemporary landscapes.
Timber sleeper wallsWarm, natural, and budget-friendly for smaller height changes. Note: timber can warp/rot over time and is vulnerable to pests vs. concrete/masonry.

For structural longevity around a new home, concrete or masonry walls are typically preferred as they won’t rot, warp, or attract termites, and they resist the heavy loads common to house platforms.

Approvals, Engineering & Drainage (Don’t Skip These)

Engineering plans: Ensure footing design, post spacing, and loads are correct.
Council/permit checks: Heights, boundaries, easements, and combined wall+fence rules may apply.
Drainage design: Granular backfill, geotextile, and weepholes/pipework to relieve water pressure.
Survey: Confirms exact boundaries to avoid costly disputes or rework.

Build Sequence for a Smooth New-Home Journey

Site assessment (levels, soil, services, boundaries).
Design & engineering (select wall type; confirm heights/lines).
Approvals & neighbour agreements (if on/near boundary).
Wall construction & drainage (before slab to secure the platform).
Fencing & services (integrate neatly with your new wall).
House construction (on a stable, compliant site).

Why Square Gardens

End-to-end: Survey, engineering, approvals, construction.
All materials: Concrete sleepers, masonry/block, stone, brick, gabion, timber.
New-build specialists: We coordinate with your builder for timing, access, and compliance for Retaining Walls on Sloping Block

📞 Call Square Gardens on 0425 015 911 for a site check and quote before you build.