Retaining walls have many purposes in the home garden. Whether you instal a retaining wall to create new levels in your garden, make a flat lawn area where there was once a sloping section or create a clear boundary, the design principles are the same.
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Retaining walls have many purposes in the home garden. Whether you instal a retaining wall to create new levels in your garden, make a flat lawn area where there was once a sloping section or create a clear boundary, the design principles are the same.
A gravity wall is a retaining wall that relies on its weight to withstand the pressure of the soil behind it. Gravity walls can be built with timber, concrete or stone and are the most common retaining walls used in domestic gardens.
Cantilever walls are usually made with poured concrete and are secured by deeply grounded foundational pillars. A cantilever wall must be professionally designed and engineered as its purpose is to hold back a significant amount of soil and often at a height.
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A cost-effective and timeless choice, a timber retaining wall can enhance your outdoor space and help deal with complex landscapes. Wood retaining walls are popular in domestic gardens.
A long-lasting and practical solution, a stone retaining wall is the perfect option for any garden and are ideal in driveways.
Another robust choice that provides endless options, keystone walls are ideal for driveway boundary lines.
New Zealand gardeners love their timber retaining walls. They are a cost-effective option for the simple garden wall, built with treated pine posts and rails.
Timber retaining walls add interest and can help to turn tricky garden areas or sloping sections into functional or usable spaces.
Wooden walls are relatively easy to build and add to the natural aesthetic of your garden. Timber walls can be stained or left to weather over time.
Building a timber retaining wall provides a great combination of strength, affordability, and aesthetics.
Timber is also a DIY-friendly choice. Provided you have access to the correct tools. You can tackle the project over a weekend.
As with everything to do with landscaping and construction, ensuring you get the foundations right from the outset is critical.
Before you get stuck into your project, you must consider the following:
Before you can begin, you must assess the ground you are planning to build on. A sloped section may require pre-earthworks or require that you change your plan. If earthworks are necessary, this will add to the cost of your project.
Ensuring adequate drainage behind your retaining wall is critical to its success. Without it, you will compromise the wall’s integrity which, ultimately, will pose a real risk. Inadequate drainage will water-log the footings and lead to the wall’s collapse.
A retaining wall over 1.5 m in height will require building consent. You will also require consent if your wall is within 1.5 m of a driveway or building.
If your wall requires building or resource consent, it must be designed by a registered engineer. Concrete and masonry walls can be designed following New Zealand standards. Still, we suggest you have the design inspected by a structural engineer as an extra layer of insurance.
According to the AUP rural zoning rules, any retaining wall that exceeds 1.5m in height is considered a building. Therefore, all requirements under the AUP relating to a building apply to a retaining wall that exceeds 1.5m in height.
Jump in this link to access Auckland Council’s Retaining Wall Guide
The wall and everything related to it, including drainage and fill, must exist within a shared boundary line. Anything that infringes the boundary can be deemed illegal and result in a costly legal battle with your neighbour. Taking the time to plan your project will avoid this issue altogether.
If you plan to incorporate fencing or planting elements, you will need to plan for these extras at the beginning. Anything outside the basic construction project requires allowances that will impact how you tackle the project.
Retaining walls must be constructed with drainage in behind and backfilled with scoria or free-draining gravel.
Ensuring adequate drainage behind your retaining wall is critical to its success. Without it, you will compromise the wall’s integrity which, ultimately, will pose a real risk.
Inadequate drainage will create a build-up of water behind the wall, water-log the footings, undermine its weight-bearing ability and lead to its collapse.
Failure to install good drainage behind your retaining wall can create a run-off of water that can impact other parts of your property and, worse still, your home. Before starting your project, take the time to research your options or discuss with an expert to avoid a costly and stressful disaster.
In today’s climate, the equation of increased demand and short supply results in a volatile market and much uncertainty surrounding the cost of building materials, except the certainty that they are on the rise.
Jump on this handy online retaining wall calculator to gain a real-time estimate for your project.
A retaining wall over 1.5 m in height will require a building consent. You will also require consent if your wall is within 1.5 m of a driveway or building.
Any retaining wall that encroaches a boundary line must have the approval of the affected party. If your neighbour agrees to your proposal, the retaining wall must become the new boundary fence despite being over the official boundary.
