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Council Approval & Engineering

Do I need an engineer for my retaining wall?

In South Australia, retaining walls over 1 metre high generally require both council approval and a qualified engineer’s design.
Approval is also usually needed if:

  • The wall is combined with a fence and total height is over 2.1 metres

  • It’s built on an easement

  • It’s on a steep slope or in an area prone to soil erosion

  • It may impact a neighbour’s property

At Square Gardens, we work closely with trusted engineers and Adelaide councils to make sure your retaining wall is fully compliant and structurally sound from day one.

Can I do my own council approval?

Yes — but you’ll need:

  • 2 copies of engineering design plans

  • Certificate of Title

  • 2 site plans showing wall height and position

  • A building certifier to inspect during construction

  • Council application fee

DIY approvals usually take about 10 weeks, but timelines vary by council. We can prepare, submit, and manage your application so you don’t have to stress over paperwork.

Drainage & Stability

Why is drainage so important for retaining walls?

Without proper drainage, water can build up behind your wall, increasing pressure that can lead to cracks, movement, or even collapse.
At Square Gardens, we use:

  • Granular backfill to help water flow freely

  • Weep holes (approx. 100 mm diameter) spaced at regular intervals

  • Geotextile fabric to stop soil from clogging your drains

Good drainage isn’t just important — it’s what makes a retaining wall last decades instead of years.

Boundaries & Cost Sharing

Who pays for my retaining wall?

When a retaining wall is on a boundary, costs are generally split based on how much each property benefits.
For example, if your side retains 300 mm and your neighbour’s side excavates 700 mm, costs might be split 30% / 70%.

We can help facilitate these agreements so both parties are on the same page.

Can I build my retaining wall on the property boundary?

Yes, but it’s important to:

  • Confirm your boundary line (via a surveyor or property plans)

  • Check council regulations — some require setbacks of 600–900 mm unless both neighbours agree

  • Be aware of Development Act 1993 rules, especially if your property is over 450 m² or near the front road boundary

We’ll guide you through every step to make sure your wall meets all legal requirements.

Cost & Materials

What’s the cheapest retaining wall in Adelaide?

The most budget-friendly option is usually timber sleeper retaining walls — quick to build and low in upfront cost.
However, they may need replacement sooner than concrete sleepers or block walls, which last much longer and require less maintenance.

At Square Gardens, we help you choose a solution that balances cost, appearance, and long-term value.

What’s the best retaining wall material for my block?

The ideal retaining wall material depends on your soil type, slope, drainage, and style preferences:

  • Concrete sleepers – Highly durable, perfect for Adelaide’s clay soils and sloped sites

  • Timber sleepers – Cost-effective and natural-looking, best for level or mild slopes

  • Block or stone walls – Premium look and high strength, great for architectural landscapes

We’ll assess your block and recommend the best option for your specific site conditions.

What’s the most durable retaining wall in Adelaide?

Steel-reinforced concrete sleeper walls are generally the most durable, lasting 50+ years when paired with proper drainage and engineering.
Other strong options include:

  • Stone or masonry block walls – Built for structural stability and style

  • Gabion walls – Steel mesh cages filled with rock, ideal for heavy-duty support

We specialise in building walls that are both tough and visually impressive.

Need More Help?

Whether you need advice on council approval, engineering, or choosing the right material, the Square Gardens team is here to help.
We handle everything from design to construction across Adelaide so you can enjoy a wall that’s built to last.

📞 Call Square Gardens today for a free site consultation and quote.

Quick FAQs – Retaining Walls Adelaide

Q: Do I need council approval for a retaining wall in Adelaide?
Yes, for walls over 1 m, combined with fences over 2.1 m, on easements, or retaining steep slopes.

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Q: What’s the cheapest retaining wall in Adelaide?
Timber sleepers are usually cheapest upfront; concrete sleepers last longer.

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Q: What’s the best material for my block?
It depends on soil, slope, and style — concrete sleepers, timber sleepers, block, stone, or gabion.

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Q: What’s the most durable retaining wall in Adelaide?
Steel-reinforced concrete sleepers can last 50+ years with proper drainage.

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Q: Can I build on the boundary?
Yes, but check boundaries and council rules — some require a 600–900 mm setback.

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Q: Who pays for a shared wall?
Costs are split based on the benefit to each property.

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Q: Why is drainage important?
It prevents water pressure from damaging or collapsing the wall.

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