Before building a retaining wall, it is important to know whether you will require council or engineer approval for the wall that you are planning. There are two main factors that determine whether you need approval – council regulations and the capabilities of the retaining wall block itself.
Each council sets it’s own regulations about maximum retaining wall heights so your first port of call should be your local council, either on the website, phone or in person. Most often, councils in Queensland allow you to legally build walls up to 1 metre without further approval, but it is best to check to be sure. Below are some links to the relevant page in a few major council regions.
When it comes to the structural capabilities of the retaining wall system, check the specifications and read any available engineering guides before building your retaining wall. TrendStone, for instance, can be built up to 865mm (4 courses + cap) on a road base footing, 1065mm (5 courses + cap) on a concrete footing, and up to 6 metres with engineer design & approval.
Always be wary that the manufacturers recommended heights are based on a set of ‘normal’ conditions including the pressure placed on the wall and the slope of the land. If you plan to drive near your wall or the ground is significantly sloping, ensure that your planned wall is within the recommended parameters outlined in the engineering guides.
If your planned wall is greater than the approved height in your council area or outside the height specifications of the block manufacturer, you will need to get an engineer to design the wall and then lodge a building permit application with your council.
If you have the space, consider a terraced wall as a way of keeping your wall within manufacturers specification whilst still retaining to the same height and saving you the hassle of additional approvals.