Retaining walls are one of those features that many property owners only think about when they need one, and that’s where a lot of confusion begins. Over the years, plenty of myths have circulated about retaining walls: how they’re built, what approvals they need, and how long they last. The truth is, retaining walls are structural systems that require proper design, engineering, and installation to perform safely and stand the test of time.
“Retaining walls under 1 metre doesn’t need engineering.”
This is one of the biggest misconceptions. While some small walls may not require council approval, that doesn’t mean they don’t need proper design. Even low retaining walls are under constant pressure from soil movement, water, and load from above. If the wall fails, it can cause property damage, drainage issues, or even safety hazards. In many cases, walls under one metre still require engineering if:
- They’re near a boundary or building
- They support a fence, driveway, or other structure
- The soil is unstable or sloping
- Local council policies require certification
Truth: Always check with your council and engage a qualified engineer, it’s cheaper than rebuilding a failed wall later.
“All retaining walls are basically the same.”
Not even close. Retaining walls come in many types, each suited to different soil conditions, heights, and load requirements. Common systems include:
- Concrete sleeper walls: Durable and low maintenance, ideal for residential and commercial use
- Panel and post walls: Heavy-duty systems perfect for high walls and industrial sites
- Reinforced concrete walls: Custom-engineered for extreme loads and long-term strength
- Gravity block walls: Used in landscaping or tiered garden applications
Each system has unique construction methods, cost profiles, and engineering needs.
Truth: The right retaining wall depends on your site conditions, purpose, and budget, not a one-size-fits-all approach.
“Timber retaining walls are just as good as concrete.”
Timber walls can look great and may be suitable for short-term landscaping projects, but they’re no match for reinforced concrete in longevity or strength. Timber is vulnerable to:
- Rot and decay from moisture
- Termite attack
- Soil pressure over time
- UV exposure and cracking
Concrete systems, by contrast, are engineered, weather-resistant, and built to last 40+ years with minimal maintenance.
Truth: Timber may be fine for decorative garden edges, but for structural or long-term applications, concrete is the smart choice.
“Drainage isn’t that important.”
Ask any retaining wall specialist what causes most failures, and you’ll hear the same thing, poor drainage. When water builds up behind a wall, it creates hydrostatic pressure, which can crack, bulge, or push the wall forward. Drainage isn’t optional; it’s essential. Proper drainage design includes:
- Ag pipes behind the wall
- Free-draining gravel backfill
- Filter fabric membranes to prevent blockages
Truth: The best-built wall in the world can fail without proper drainage. Always include professional water management in your design.
“You can build a retaining wall anywhere on your block.”
Many property owners assume they can install a retaining wall wherever they like, but council setback rules and boundary regulations apply. In Western Australia, approvals depend on factors such as:
- Wall height and proximity to boundaries
- Whether it retains neighbouring soil
- Zoning and land development codes
Building too close to a boundary without permission can result in compliance issues or disputes with neighbours.
Truth: Always check with your local council or a licensed contractor before construction begins.
“Retaining walls don’t need maintenance.”
Even the strongest retaining wall benefits from occasional inspection. Over time, environmental conditions can cause movement, surface cracking, or blocked drainage. Simple maintenance can extend the wall’s life dramatically:
- Check for leaks or pooling water
- Remove weeds or roots near the wall
- Keep drainage lines clear
- Avoid placing heavy loads right at the wall’s edge
Truth: Preventative maintenance is cheap, repairs are not.
“The cheapest quote is the best deal.”
A low quote can be tempting, but it often means corners are being cut, whether on material quality, engineering, or drainage. Walls built without proper foundations or certification may fail within a few years, turning a “cheap” job into an expensive rebuild.
Truth: Always compare scope and inclusions, not just price. A properly engineered wall is a long-term investment, not a short-term saving.
“DIY retaining walls are easy to build.”
While small garden edging or planter walls can be DIY projects, structural retaining walls are not. They require:
- Geotechnical knowledge
- Structural engineering design
- Correct compaction and drainage installation
- Compliance with local council requirements
Without these, you risk creating a wall that looks fine initially but fails under pressure later.
Truth: For any wall over 600mm high or supporting loads, hire a licensed retaining wall contractor to ensure safety and compliance.
Build on Facts, Not Myths
When it comes to retaining walls, the key to saving money and avoiding headaches is simple, build it right the first time. Understanding how design, materials, and drainage work together will protect your investment and ensure your wall lasts for decades.
Talk to Perth’s Retaining Wall Specialists
Have questions about your retaining wall project? Don’t rely on myths or guesswork, get the facts from the experts. Contact Structural Retaining Walls today to arrange a site inspection or request a quote.