What you need to know about DIY retaining walls
12 June 2018
Retaining walls are often used in residential and commercial landscaping applications to retain soil, reduce land erosion, and to level off sloping land.
Retaining wall blocks are designed to be easy to build and DIY friendly for the weekend renovator. Before you get started, you may have some questions about height restrictions, engineering, and council approval, so we've complied a list of the most common questions asked when considering building a retaining wall at home.
DIY retaining walls - Get the facts
Your local council sets the maximum height that you can build walls without approval. All councils are different and you must check with your local council as to height regulations in your area before you begin to build.
If you’re building higher than councils regulations, you will need a building permit from your local council and certification from a private building certifier as per the engineer's design.
Do I need approval to build a retaining wall?
Legislation on the construction of retaining walls is set by your local council. The ‘magic number’of 1 metre is commonly referred to as the maximum height you can build to without a permit. It's important to note that all councils differ so the best advice is to get the right advice! You can determine the regulations for retaining walls in your suburb via a quick call to your council's development team.
If the wall you are building will exceed the maximum non-engineered height set by your council, then you will need to lodge a building permit application with your local council. You will also need an engineer to design the wall and a building certifier to sign off on your handy work to complete the approval.
How high can I build a retaining wall?
There are two conditions that determine how high you can build a garden retaining wall. The first condition is the height restrictions set by your local council, and the second condition is the physical capability of the retaining wall block, or sleeper wall, that you wish to use.
Retaining wall manufacturers will specify the maximum height that products can be built to without engineering. These are often referred to as 'gravity wall heights' because the wall gains its structural integrity, and performs its retaining function, by using its mass weight to retain soil. In some cases, you may still need an engineered design to build below the council height limit – it all comes down to the capacity of the retaining wall system you use.
How do I get approval to build a retaining wall?
If your retaining wall exceeds the maximum height set out by council, you will need to gain approval before you build. There are some instances like building in soils with high clay content, or building walls that bare significant load (i.e. driveways), where you may also need approval or an engineered design for your retaining wall, regardless of the wall height. Outlined below is a checklist for your consideration before building a retaining wall.
Step 1: Check with your local council and confirm if you need approval to build the retaining wall.
Step 2: Engage a private building certifier to manage the approval process. Your certifier should;
- Submit the development application to council and lodge required forms.
- Tell you of any design / construction ‘certificates’ that are required to gain approval. These are professional "assurances" that the work is to be completed by an industry professional (i.e. a registered engineer), and ensure that the work is up to industry standard.
- Inspect the finished work and provide approval documentation which is then lodged with the council.
Step 3: Once you have approval to build, you will be issued with a building construction certificate that allows you to begin construction. Always dial before you dig - call 1100.
Get Started Now!
With your construction certificate in hand, you are ready to choose a retaining wall system and start building! For more information on how to DIY retaining walls, check out this great step by step 'How to build a retaining wall' video.
You can also check out our social media pages for more masonry inspiration