What do I need to consider before planning a retaining wall?

Retaining walls have been used for years in order to retain soil, but when cleverly designed they can provide a range of other functions.

Perhaps you would like to create different levels and structure in your yard, defining distinctive and functional multi-use spaces, or maybe you want to control the flow of rainwater better. Whatever your reason for investing in a retaining wall, our team of landscaping experts have outlined below some things to consider before planning one.

Do I need permits and engineering?

The purpose of a retaining wall is to retain your soil and garden, so it is vital that it is constructed properly. If your retaining wall is going to be over a metre in height it will require a permit, engineering and soil testing to ensure it stands the test of time under different weather conditions and landscaping functions.

Before beginning construction, you will also need to check the location of your services such as power, water and gas to ensure you don't damage any of them in the excavation process. Most services are located in your front yard, but you should always check with Dial Before You Dig before commencing any landscaping project.

In Melbourne, if your retaining wall is designed to sit close to the boundary of your property, or is being installed over an easement, you will also need a special permit from your local council. At Creative Image Landscapes, we know it can be tricky to decipher all the drawings, rules and permits, so we organise any required engineering and permits on your behalf. This way you can feel comfortable knowing you are completely covered, without lifting a finger.

Is drainage important?

Drainage may not be the first thing that comes to mind when planning your new retaining wall, but it is by far the most important factor to consider.

If you don't arrange proper drainage before or after installing your retaining wall, you can have water pooling issues, water damage to the retaining wall and surrounding elements, and your retaining wall can even lean or buckle under the excessive pressure. Be sure to check with your local landscaper that they have a drainage and membrane plan before beginning any retaining wall project.

What are the most popular material options in Melbourne?

Timber sleepers

Timber sleepers are traditionally the retaining wall material of choice, with the timber initially used for old railways years ago. Nowadays, there are a range of hardwoods or treated pine sleepers to choose from, as well as different stains to suit the aesthetic of your landscaping. The timber sleepers are supported by either strong galvanised steel or vertical timber posts, depending on your design requirements and style preferences. Galvanised steel has durability benefits, often outlasting the timber posts, but with a completely different appearance — your selection of post material really depends on the look you'd like to achieve. Timber sleepers are the most budget-friendly option and are usually used when the retaining wall is not a main feature of your outdoor space.

Concrete sleepers

Concrete sleepers are often selected for their durability, generally lasting a lifetime. The concrete is pre-cast to come in a range of styles, created to mimic the look of natural timber, smooth slate, aged stone and industrial concrete. These are installed similarly to timber, with galvanised steel posts. Concrete sleepers can provide some advantages in terms of budget, as they do not require as much waterproofing as the other materials.

Concrete masonry blocks

Concrete masonry blocks are available in a range of sizes, colours and textures. Like concrete, they are an extremely durable material, and are installed with strengthening reinforcements. These blocks are designed to be stacked, so there is no need for posts with this material. Although these blocks are generally used in commercial landscaping due to their robust aesthetic, they can be used masterfully in residential applications.

Stone cladding

Stone cladding boasts the most aesthetic flexibility of all the materials used for retaining walls, delivering the biggest visual impact. This is due to the different shapes, shades and sizes of the pieces of loose stone, creating endless design outcomes. Types of stone cladding include slate, granite, limestone, sandstone and travertine, which can all be used to create a striking retaining wall feature. The stone is generally cladded onto a concrete wall using a special adhesive, so there is no need for timber or steel posts. Its versatile nature also allows for consistency throughout your outdoor space, with the ability to use the same stone for elements such as outdoor kitchens, fireplaces and paving.

Rendered wall

Built from blocks, the rendered retaining wall can be rendered and finished with different textures and colours.

In summary

Timber and concrete sleeper retaining walls

• Best where they are not really going to be seen
• Tight access — can be built in narrow spaces and take up less room than block walls
• A cheaper alternative to other retaining wall options
• Quick and cost-effective to build

Rendered retaining walls

• Constructed of concrete blocks laid on a concrete footing and core-filled on completion, so they can be used for structural purposes (e.g. supporting a slab, mounting a pool fence, or building other structures onto)
• Perfect to tie in with the house exterior/render
• More of a feature

Stone cladding walls

• Constructed exactly the same way as rendered retaining walls — except one has render on it and one has stone
• More of a feature statement

Do I need a landscaper to construct my retaining wall?

It may seem simple to construct a timber retaining wall, however a professional landscaper has years of experience navigating issues and crafting their trade, potentially saving you from a nightmare down the track. It is common for a professional landscaper to come across DIY retaining walls tilting and falling over due to incorrect depth of post holes, no waterproofing or drainage, and a lack of engineering planning in general. The pressure of the weight of the embankment can cause serious problems, and at times can even damage the stability of your home, so it can pay to call in the experts.

Landscapers not only extensively know the do's and don'ts of retaining walls, but they have invested years in building relationships with suppliers, often sourcing products that aren't available to the public at the same prices. They can also recommend design ideas to make your retaining wall a masterpiece, such as the addition and placement of lighting and protruding benches or seating.

Retaining walls can be an attractive and practical addition to your backyard, but there are so many things to consider before beginning construction. At Creative Image Landscapes we manage all aspects of your design, planning, engineering and permits to make the best use of your space and provide a hassle-free solution for your brand-new retaining wall. If you would like some assistance in planning yours for your Melbourne home, please contact our team of experienced landscapers for some ideas!