With sloping blocks, clay-heavy soils, and a growing love for landscaping upgrades across the Gold Coast, retaining walls are a common feature in many backyards. Whether you’re levelling out a yard, supporting a garden bed, or holding back soil on a slope, these walls are essential for practical function and outdoor appeal.
One of the first questions that often gets asked is: How much does a retaining wall cost? The answer can vary, and in this guide, we’ll walk you through the costs for different materials and the key things that affect the overall cost.
Retaining Wall Cost Overview: Common Materials and Their Ballpark Prices
Timber Sleeper Retaining Walls
Estimated Cost:
- Treated Pine: Starting from $250 – $350 per square metre (supply and installation)
- Hardwood: Starting from $300 – $450 per square metre for (supply and installation)
Timber sleepers are a great option if you’re after a budget-friendly retaining wall with a natural, rustic look. Treated pine is the more affordable choice, which is ideal for garden edging or low retaining walls. Hardwood sleepers provide extra durability and a richer finish but may come at a higher price. The cost can rise up to $650 per square metre for challenging sites, complex projects or small projects where you don’t get the benefit of economies of scale.
However, timber comes with a few disadvantages. The Gold Coast’s warm and humid climate makes timber walls more susceptible to termites, rot, and weathering, which means ongoing maintenance is important to keep them in good condition. While it may cost less upfront, timber sleepers have a shorter lifespan compared to alternative materials like concrete.
Concrete Sleeper Retaining Walls
Estimated Cost:
- Starting from $450 – $700 per square metre (supply and installation)
Concrete sleeper retaining walls are a durable and low-maintenance option, ideal for homeowners seeking a long-lasting solution. While the initial investment may be higher compared to timber, they offer superior strength and resistance to pests and moisture, making them well-suited for the Gold Coast climate.
Installation costs can vary depending on several factors, like the terrain and drainage requirements. However, once the concrete sleepers are installed, you don’t have to worry about upkeep, and they also last 30+ years, providing excellent value over time.
Concrete Block Retaining Walls
Estimated Cost:
- Starting from Interlocking concrete blocks: $350 – $600 per square metre (supply and installation)
- Starting from Besser Blocks: $550 – $750 per square metre (supply and installation)
Concrete block retaining walls can come in different styles, such as interlocking blocks and Besser blocks. The cost depends on the type of block and how the wall is built. Interlocking blocks are designed to fit together easily without mortar, which makes them quicker and cheaper to install. They’re great for garden walls and tiered landscapes where flexibility and design are key.
On the other hand, Besser blocks are used primarily as structural retaining walls that need to hold back heavy loads. They require more labour and materials to build but provide strong, long-lasting support for demanding projects.
Sandstone Retaining Walls
Estimated Cost:
- Starting from $400 – $600 per square metre (supply and installation)
Sandstone retaining walls are all about natural beauty and long-lasting durability, making them a premium choice for many homeowners. The cost varies depending on the type of sandstone and installation. A-grade cut sandstone blocks have a smooth, consistent finish with minimal variation, and sit at the higher end of the price range. B-grade sandstone is a more affordable option, featuring a rougher texture and natural colour variations. If you want a more rustic and rugged look, random sandstone boulders create a more organic feel.
While sandstone retaining walls can last up to 50 years or more with proper care, it does come with a higher upfront cost compared to materials like timber or interlocking blocks. Installation can also be labour-intensive, and site access and terrain can also affect the overall cost. Despite these, many homeowners choose sandstone for its timeless look and ability to blend seamlessly into natural landscapes.
Factors that Influence the Cost of a Retaining Wall
When planning to build a retaining wall, many homeowners focus on the length and height as the main cost drivers. While these are important, there’s a lot more that can affect the overall price. Factors like site access, drainage, and the details of the retaining wall installation process all play a role in shaping the final cost.
Site Access
The ease of access to your property plays a major role in determining labour and equipment costs. If machinery can reach the area easily, installation is faster and more affordable. But if access is limited, like working in tight spaces or steep slopes, expect costs to rise due to extra labour and manual handling.
Soil Type and Ground Conditions
Soil quality can significantly affect how your retaining wall is built. On the Gold Coast, reactive clay soils are common. These expand and contract with moisture, which means your retaining wall needs deeper footings, additional stabilisation, or reinforced materials to keep it stable. These reinforcements add to the overall cost.
Drainage Requirements
Proper drainage is crucial to prevent water from building up behind your wall. If not done properly, this can lead to structural failure. Installing drainage systems like agg pipes, gravel backfill, and geofabrics adds extra material and labour costs, but they are essential for the wall’s long-term performance. Working with a QBCC-licensed contractor increases the likelihood that the contractor will follow best practices when building a retaining wall, protecting your property and avoiding future headaches.
Wall Height
Walls over one metre generally require engineering certification and council approval, which can affect both the design and cost. Factoring in these approval requirements for retaining walls early can help avoid unexpected delays. Taller walls also require more reinforcement, which increases material and labour costs.
Material Quality and Finish
Not all retaining wall materials are created equal. Premium finishes like custom-coloured concrete sleepers or A-grade sandstone blocks will cost more than standard options. While higher-grade materials come with a bigger upfront price, they can offer better longevity and visual appeal, which are worth the investment.
Choosing the Best Retaining Wall for Your Budget and Style
The cost of a retaining wall on the Gold Coast can vary widely and also depends on several factors like materials, design, and site . Whether you’re leaning toward timber for its affordability, concrete for its durability, or sandstone for its premium finish, the right choice comes down to balancing budget, longevity, and the look you want for your space. Considering these elements upfront will help you get the best value from your investment.
Not sure what’s right for your backyard? Call us on (07) 5651 0669 so you can tell us what your plans are and we’ll sort out the best options and costs for your space! As an experienced retaining wall builder on the Gold Coast, we know how to turn tricky slopes and outdoor spaces into something functional and beautiful.
