The waterproof membrane for retaining walls needs to be chosen correctly. Incorrect selection can affect the longevity of the retaining wall structure.
Get the Expert Lowdown on Retaining Walls
From codes and regulations to retaining wall material options, there is a solution for every slope on your property
Steve Taylor Houzz Australia Contributor. Managing director of COS Design. Landscape, pool, alfresco and home designer based in Melbourne.
Having visited hundreds of Australian gardens, I would say that sloping sites represent 60-70 per cent of our residential blocks, with the degree of slope varying depending on the natural topography of the land or how it has been developed. Slopes can create many challenges when designing a garden with functional and usable spaces and the costs can really blow out. However, when managed well, effective terracing and the use of retaining walls can become a valuable design feature of your landscape
Photo by Envision Landscape Studio – Discover garden design ideas
Retaining walls come in many different forms, all with varying cost implications, so let’s explore your options and present some great design tips to help you manage your sloping site.
C.O.S Design
Know your retaining wall
When we have a completely flat block we often add height and interest with raised planter boxes and feature walls, so don’t be scared of retaining walls, embrace them. You don’t always require extensive retaining walls either, as maintaining the natural slope, or a combination of the slope and more strategic use of retaining structures, can also create a great look.
Peter Glass & Associates
There are two aspects (or directions) to a retaining wall.
1.I call the first type of retaining wall a ‘negative wall’ and this is where the retaining wall faces away from the main view and it retains a higher ground level in the foreground. These walls are not really seen (as shown in this photo) and they can be a lower-cost option.
Contemporary Deck by Scott Weston Architecture Design PL
2. The second is a ‘positive wall’ and this is where the wall faces the main view or vista and retains a higher section of the garden in the background, as in this home. These walls need a higher level of investment as they are a permanent visual feature. So it is wise to spend as little money as possible on any negative walls and invest more in the positive walls.
Codes and regulations
With any project, it is important to first be familiar with the building codes and regulations that affect you and to make sure you comply with these when building any walls. Laws regarding engineering vary from state to state and from council to council; some areas require engineering with any wall above 600mm and other areas allow walls under 1,000mm to be exempt. You need to check your local laws. If unsure it is always safer to engage an engineer, particularly if the retaining wall will support land outside your ownership, big trees or load-bearing structures.
Huettl Landscape Architecture
Second to this, any retaining wall with a build cost of more than $5,000 often requires a permit, and walls over $16,000 require builders warranty insurance. Make sure you build your wall in accordance to these regulations to ensure everything is above board.
Also, you will need to find out your soil type to determine its effect on the performance of the foundations and footings. Finally, ensure there is excellent drainage and waterproofing behind every wall – the life expectancy and structural performance will be greatly improved.
JPR Architects
Retaining options
There are many options for dealing with tricky terrains; the type you choose to use will be based on a number of factors including your budget, the incline of your slope, local codes/regulations, accessibility compliance and desired design aesthetic.
