Retaining Wall Quotes & Cost Guide 2025

Retaining walls are structures designed to confine soil to a slope that it would not naturally keep to; typically a steep, almost vertical or vertical slope. Retaining walls are found in residential, commercial and civil properties and are used to 'hold the earth back' - literally and figuratively. The wall's purpose is to bound soils between two different elevations often in areas of terrain that are sloped, or in areas where the landscape needs to be shaped substantially and engineered for more specific purposes like hillside farming or roadway overpasses.

Read more about what a retaining wall is on the blog.

Treated pine or other types of wood sleepers, tends to be the cheapest option at around $250 per square metre. The other options include hardwood, concrete sleepers, besser blocks or natural stone, etc. Timber and dry-stacked stone walls are usually the most cost-effective types of retaining walls.

Whether you need retaining wall repair or want to get a new one built at a reasonable price, you can find a supplier through iseekplant with our Get a Quote tool.

These are usually the conditions under which you need a retaining wall:

• Slope exceeds 2:1 (Horizontal:Vertical): That means for every 2 metres horizontally, the land drops more than 1 metre. This is around a 26.5° slope — this is considered steep and prone to erosion.
• There’s risk of soil erosion or slippage*: Especially in areas with clay-heavy soils or frequent rain, even milder slopes might need a wall to prevent movement.
• You're cutting into a slope to build: Excavating into a hill to make flat space (for patios, paths, driveways, etc.) often exposes a vertical soil face that needs to be held back.
• You want to level a sloped yard: Terracing with retaining walls can create usable flat areas for gardening, entertaining, or structures.
• Water runoff is causing problems: If water is flowing downhill and pooling or washing out areas, a retaining wall with proper drainage (e.g. ag pipe behind it) can redirect it.
• Your council requires it: In many places (including in Australia), a retaining wall over a certain height (commonly 600mm) or load-bearing may need approval and engineered plans.

In most Australian states, retaining walls up to 1 metre high can be built close to the boundary. However, always check local council regulations for specific distances.

Yes, for walls higher than a specific height, usually 1 metre, you'll need planning permission, but this varies by council. Always check local regulations.

In Australia, if the retaining wall is over a certain height (typically 1 metre) or supports a load like a driveway or other structures, you'll need a licensed builder or structural landscaper to construct it.

The whole purpose of iseekplant - is to help you find verified suppliers close to your jobsite. As such, you can literally search iseekplant for any of the 16,000 postcodes in Australia and it will return a list of suppliers that are ranked by proximity to your job.

iseekplant has a huge network of retaining wall companies operating in all Australian capital cities from Brisbane to Sydney, Canberra, Melbourne to Darwin, Perth and Adelaide. We also offer retaining wall solutions in all major towns and cities from Cairns down to the Sunshine Coast, Gold Coast, Newcastle, Central Coast and then across the country to Bunbury.

Finding a retaining wall contractor through iseekplant is a hassle-free process. iseekplant is a giant directory, so you can search on our platform and it will return a list of suppliers ranked by proximity to your job.

To get fast and free quotes for retaining wall construction or retaining wall repairs in your area, all you have to do is to use iseekplant's get a quote tool. Alternatively, you can call us on 1300 691 912 or email us at projects@iseekplant.com.au.

You’ll likely need a structural engineer if:

• The wall exceeds 600mm in height: Most local councils require engineering approval for retaining walls taller than 600mm (0.6m), though this can vary by location.
• The wall supports a load above it: For example: a driveway, building, fence, pool, or parked vehicle. Any structure exerting force on the wall requires engineering to ensure stability.
• The soil is reactive, sandy, or unstable: An engineer will assess geotechnical factors to design a wall that won't fail over time.
• Drainage is complex or the wall must handle significant water flow: Poor drainage causes most wall failures. Engineers ensure the wall includes proper behind-wall drainage (like ag pipe, scoria, weep holes).
• You’re using certain materials (e.g., concrete sleepers, reinforced block walls): These systems often need engineered footings and reinforcement to meet code.

You’ll likely need a surveyor if:

• The wall is built on or near a property boundary: To avoid encroachment disputes, a surveyor will mark the legal boundary lines.
• You’re in a sloped or hilly area where property boundaries are unclear: Surveyors help determine exact contours, slope angles, and boundary compliance.
• Local council requires a formal site plan or elevation drawings for approval: A surveyor provides certified measurements and maps for planning submissions.

Here are our top tips for saving money on a retaining wall:

• Stick to ≤600mm height if possible — avoids the need for engineering, council approval, and compliance costs.
• Use gravity wall systems (like interlocking blocks or sleepers) that don’t need reinforcement or mortar.
• DIY where safe and legal — smaller walls under 600mm can often be built without hiring professionals.
• Choose cost-effective materials like treated pine sleepers or concrete blocks over natural stone or sandstone.
• Buy in bulk — materials like blocks, gravel, and sleepers are cheaper per unit when purchased in pallet or bulk quantities.
• Source from local quarries or landscape yards to reduce delivery and material costs.
• Look for seconds or surplus stock from builders, Gumtree, or Facebook Marketplace — especially sleepers and blocks.
• Use crushed rock or gravel as backfill instead of expensive drainage solutions, as long as it drains effectively.
• Avoid complex shapes — straight walls are cheaper and easier to build than curved or terraced ones.
• Keep it away from property boundaries to avoid surveyor costs and disputes.
• Reuse site soil for backfilling if it drains well and is stable, instead of buying new fill.
• Plan for proper drainage upfront — preventing future damage saves you from costly repairs.

On iseekplant, we consider there to be broadly 7 types of retaining walls, and we have created subcategories for these as follows:

Block Retaining Wall: These walls feature interlocking modular blocks, creating a sleek, contemporary look while ensuring structural stability. Rock Retaining Wall: Constructed by stacking sizable natural rocks, these walls deliver both rugged durability and an organic appearance. Gabion Retaining Wall: Formed from wire mesh cages packed with stone or concrete, gabion walls provide a robust and adaptable solution for erosion control and landscaping. Boulder Retaining Wall: Using large, heavy boulders strategically placed, these walls are ideal for stabilizing sloped terrain and managing substantial earth pressure. Concrete Sleeper Wall: Built using vertical concrete posts with horizontal sleepers, these walls are a popular choice due to their long-lasting strength and clean finish across various settings.

There are also other types of retaining walls that our contractor can help you create, but these aren't subcategories on iseekplant, so feel free to ask your contractor if they can assist:

1. Gravity: Gravity walls are designed based on their mass (stone, concrete or other heavy material) to resist pressure from behind and may have a 'batter' setback to improve stability by leaning back toward the retained soil.
2. Diaphragm Wall: These walls are very stiff and generally watertight. Diaphragm walls are expensive, but they save time and space and are commonly used in urban constructions.
3. Bored Pile: Bored Pile walls are built by collecting a sequence of bored piles, proceeded by excavating away the excess soil. Depending on the project, the bored pile retaining wall may include a series of earth anchors, reinforcing beams, soil improvement operations and concrete reinforcement layer.
4. Anchored Walls: An anchored retaining wall can be constructed in any of the other retaining walls styles but also includes additional strength using cables or other stays anchored in the rock or soil behind it.
5. Sheet Piling: Generally used in soft soil and tight spaces, sheet pile walls are driven into the ground and are composed of a variety of material including steel, vinyl, aluminium, fibreglass or wood planks.

Read our types of retaining wall blog post to find out more about each type of retaining wall.