Temporary retaining walls are short-term structures designed to hold soil during construction or excavation. Permanent retaining walls are engineered structures built to retain soil for the long term and form part of the finished property. Permanent walls are designed for durability, compliance, and decades of performance, while temporary walls are designed for limited use and removal.
When should a temporary retaining wall be used?
A temporary retaining wall should be used when soil needs to be held back only during construction, excavation, or short-term works. These walls are commonly used on building sites, basement excavations, and service installations where the soil will later be supported by permanent structures.
When is a permanent retaining wall required?
A permanent retaining wall is required whenever soil levels will remain altered long-term. Permanent walls are needed for boundary retaining, sloping blocks, landscaping, driveways, fences, and any situation where soil must be retained safely and compliantly for the life of the property.
Why Understanding the Difference Matters
Choosing the wrong type of retaining wall can lead to serious problems. A temporary wall used where a permanent wall is required can fail, cause soil movement, create drainage issues, or result in council compliance action. On the other hand, installing a permanent wall where only temporary support is needed can add unnecessary cost to a project. In Perth, where soil conditions vary widely and council regulations are strict, understanding when each type makes sense is critical.
What Is a Temporary Retaining Wall?
A temporary retaining wall is a short-term structure designed to hold back soil for a limited period. These walls are commonly used during construction phases and are not intended to last once the project is complete. Temporary retaining walls are typically installed to support excavations for basements, footings, service trenches, or cut-and-fill works. Once the permanent structure is built, the temporary wall is either removed or no longer relied upon. Because they are short-term, temporary retaining walls are not designed for long-term exposure to water, weather, or ongoing soil pressure.
Common Uses for Temporary Retaining Walls
Temporary retaining walls are often used on construction sites where soil support is needed briefly. In Perth, this includes residential builds on sloping blocks, commercial developments, and civil works. They are commonly used during excavation for house footings, basement walls, underground services, and site cuts where permanent retaining will be installed later. In some cases, temporary walls support soil until concrete slabs or permanent structures are poured and are capable of carrying the load.
Limitations of Temporary Retaining Walls
Temporary retaining walls are not designed to last. They are typically built with lighter materials, reduced footing depth, and minimal drainage because their lifespan is limited. If left in place long term, temporary walls are prone to movement, water damage, and collapse. They are not suitable for supporting fences, driveways, landscaping, or boundary soil on an ongoing basis. Using a temporary retaining wall as a permanent solution is one of the most common causes of failure and disputes.
What Is a Permanent Retaining Wall?
A permanent retaining wall is a fully engineered structure designed to hold soil safely for decades. These walls form part of the finished property and are built to handle long-term soil pressure, water load, and any additional forces such as fences, vehicles, or structures above the wall. In Perth, permanent retaining walls must comply with AS 4678 – Earth-Retaining Structures and meet local council requirements. Permanent walls are typically constructed using concrete sleepers, panel-and-post systems, reinforced concrete, or other durable materials designed for Australian conditions.
Common Uses for Permanent Retaining Walls
Permanent retaining walls are used wherever ground levels are altered on a long-term basis. This includes boundary retaining between properties, terraced yards, sloping blocks, driveways, pool areas, garden levels, and commercial or civil developments. They are also essential where a wall supports a fence, garage, shed, or driveway, or where failure would impact neighbouring properties.
Why Drainage Is Critical for Permanent Walls
One of the biggest differences between temporary and permanent retaining walls is drainage. Permanent walls must manage water effectively for decades. Proper drainage systems reduce hydrostatic pressure and prevent movement or cracking. In Perth’s winter rainfall conditions, poor drainage is the leading cause of retaining wall failure. Permanent retaining walls are designed with ag pipes, free-draining backfill, and controlled discharge points to manage water safely.
Engineering and Compliance Differences
Temporary retaining walls may still require engineering on larger or deeper excavations, but they are generally designed for short-term loads only. Permanent retaining walls, however, almost always require engineering when they exceed certain heights, sit near boundaries, or support surcharge loads. In Perth, walls around one metre or higher, or those near property lines, typically require engineering certification and council approval. Permanent walls must also meet stricter footing, material, and construction standards to ensure long-term stability.
Cost Considerations: Temporary vs Permanent
Temporary retaining walls are usually cheaper upfront because they use lighter materials and simpler construction methods. However, they offer no long-term value and must be removed or replaced. Permanent retaining walls cost more initially but provide lasting structural support, compliance, and property value. Over the full lifecycle, a permanent wall is almost always the more cost-effective solution when long-term soil retention is required.
Choosing the Right Option for Your Project
The right retaining wall depends on the purpose and timeframe of your project. If soil only needs to be retained during construction and will later be supported by a permanent structure, a temporary wall may be suitable. If soil levels will remain altered, if the wall is near a boundary, or if it supports fences, driveways, or landscaping, a permanent retaining wall is essential. Getting this decision wrong can lead to structural failure, council orders, neighbour disputes, and costly rebuilds. Speak with the experts at Structural Retaining Walls today.