Complete Guide To Panel And Post Retaining Walls

Sloping land is one of the most underestimated headaches in Perth property ownership. Panel and post retaining walls are the retaining system we build most often to retain soil, level yards, and create usable ground where a slope made the space unusable. This panel and post retaining walls guide covers materials, council approval, construction, and real project costs from recent FencrGatr builds. Contact us on 1300 441 366 for a site measure and quote.

How Panel And Post Retaining Walls Work

The concept is straightforward. Vertical posts go into the ground. Horizontal panels slot between them. The wall is constructed so that posts carry the lateral load from the soil, and the panels act as the barrier.

What makes this retaining system so widely used across Australia is its adaptability, from 200mm garden edging to engineered walls at 1.5 metres. The structure relies on post depth for stability, each post set into a hole, packed with concrete at the correct consistency, and cured before panels are fitted. Panels sit in channels on each post and can be timber sleepers, concrete sleepers, or galvanised steel depending on the look and durability the site demands. The method has been developed over decades for residential landscape projects.

Choosing Your Panel Material

This decision shapes the cost, the style, and how long the wall stands. Get it wrong and you will be rebuilding inside ten years.

Timber sleepers give you a natural look for garden beds and yard landscaping at the lowest price point. Treated pine is the cheapest, while jarrah costs more but offers greater durability. Timber does need waterproofing on the soil side and will break down after 15 to 20 years depending on drainage and ground contact.

Concrete sleepers from manufacturers like Boral and Austral Masonry are the panel we recommend most. They come in colours and textures that mimic sandstone, ironbark, or rammed earth, delivering genuine aesthetic appeal with the durability of reinforced concrete. We use them on most FencrGatr projects because the cost sits mid-table but the lifespan leads every other option.

Galvanised steel panels suit boundary retaining where appearance matters less. Lightweight, quick to install, and they tie in well with colorbond fence panels above the wall.

Planning And Council Approval

Skip this step and the council may make you tear it down. Before you dig, determine whether your proposed wall requires council approval. In most Perth councils, any retaining wall over 500mm needs a building permit. If the proposed wall sits on or near a boundary, the rules tighten further.

Measure the change in ground level across your site. Use a string line and spirit level between the first peg at the high point and a second peg at the low point to determine the slope. This tells you the height and length of wall you need. Note the positioning of services and tree roots before deciding on the wall line.

Engineering is essential for walls over 500mm because the load calculations determine post depth, spacing, and footing size. We engage a structural engineer and handle the council approval process so homeowners do not have to navigate the planning guidelines themselves. The clay soils through Gosnells and the Darling Scarp foothills exert significantly more lateral pressure than sandy coastal ground, and the engineering reflects that. Getting this wrong leads to catastrophic failure.

How We Build A Panel And Post Retaining Wall

Once planning and council approval are sorted, here is how the construction unfolds.

We mark the wall line using a string line tied between pegs and set to finished height with a spirit level. The first post goes at one end, remaining posts spaced to match panel length, typically 2.4 metres centre to centre. We dig each hole to the required depth. For a 1 metre wall, posts need 900mm to 1,200mm in the ground to achieve the stability the engineer specifies.

Each post goes into the entire hole plumb and braced. We fill around it with cement and concrete mixed to the correct consistency. Posts cure before any load goes on, which is why we set all posts on the same day and return to fit panels once hardened. Loading panels onto green concrete shifts the posts, and you end up with a wall that is not the same height along its length. We refuse to do that.

Panels slot in from the top, starting at the bottom row. Behind the wall we install drainage ag pipe wrapped in geotextile fabric, then backfill with gravel before the retained soil goes back. Drainage is everything. Without it, hydrostatic pressure builds and pushes the structure forward. After backfill is completed, we compact in layers and finish to match the surrounding garden or yard level.

Recent Retaining Wall Projects

Here is what two recent builds looked like in practice.

Kalamunda, Stepped Retaining On A Hillside Block

A property in Kalamunda had a 22 metre rear boundary dropping 1.4 metres from house to fence line. Laterite rock underneath made augering slow, but the dense substrate meant exceptional footing stability. We built a stepped wall using Boral charcoal concrete sleepers, the lower tier at 800mm and the upper at 600mm, separated by a planted garden bed. Total cost was $8,400 including engineering, council approval, and drainage. The owners had been avoiding that slope for years. Now it is the best part of their yard.

Gosnells, Boundary Retaining With Colorbond Fence

A block in Gosnells needed 18 metres of boundary retaining at 900mm to level the backyard against a neighbour sitting higher. Heavy clay soil meant deeper posts and more concrete. We used sandstone-look concrete sleepers and ran 1.8 metre Woodland Grey colorbond fencing on top, engineered as a single structure. Total cost was $7,200 for the retaining and $2,520 for the fence. Building both together saved roughly $1,100 versus separate projects. The completed wall and fence transformed a soggy, sloping boundary into a clean, level property line.

Cost And What Affects It

Panel and post retaining walls in Perth cost $180 to $450 per lineal metre depending on wall height, panel material, and site access. A 600mm concrete sleeper wall on flat ground sits at the lower end. A 1.2 metre wall on a slope with clay soil pushes higher because of deeper posts, more cement, and extra materials.

If the retaining wall runs along a boundary and a fence sits on top, we build both as one project to save on labour and ensure the structure is engineered as a single unit. FencrGatr quotes retaining and fencing together so you see the full cost before work starts on site.

Panel And Post Retaining Wall Questions

Here are the questions homeowners ask most about this retaining system.

Do I Need Council Approval For A Retaining Wall?

In most Perth councils, any retaining wall over 500mm requires a building permit. Walls on or near a boundary line have additional requirements. We handle council approval and engineering so you can decide on the wall and leave the paperwork to us.

Can I Build A Retaining Wall Myself?

For walls under 500mm on your own property, a DIY approach is possible if you follow the same steps we use: set posts deep, concrete at the correct consistency, install drainage, and backfill in layers. Anything above 500mm needs engineering, and we strongly recommend professional construction for safety and durability. A failed retaining wall can damage your house, your neighbour’s property, or both.

How Long Does A Retaining Wall Project Take?

A standard residential wall of 10 to 20 metres takes two to three days. Posts are set and concreted on the first day, panels fitted once cured, and drainage and backfill completed on the final day. Larger walls with stepped sections take longer.

What Is The Best Material For Retaining Wall Panels?

Concrete sleepers offer the strongest balance of cost, durability, and aesthetic appeal. They come in multiple colours and textures to enhance your landscape, and outlast timber by decades. For garden beds and low walls under 600mm, timber sleepers suit a natural style at a lower price.

Get Your Retaining Wall Project Started

Whether you need to retain soil on a sloping block, create a level yard, or build a retaining wall with a fence on top, FencrGatr handles the full project from planning through to completed construction across Perth and Western Australia. Contact us for a free site measure. Call 1300 441 366 or fill in our online form.