Rendering a Retaining Wall

A retaining wall is usually found in a garden, where it supports flowers, plants, and vegetable gardens, prevents erosion, and makes sloping yards neater and easier to navigate. Some pools also feature retaining walls. While some retaining walls are simply built from brick, many people choose to render them to transform the look of their gardens and outdoor spaces. It is a cost-effective, relatively simple way to add style and interest to the outdoors.

Continue reading to learn everything you need to know about rendering a retaining wall.

Can You Render a Retaining Wall?​

Yes, retaining walls are usually built from brick, which means they can definitely be rendered. Render also works well on stone or rubble (with proper preparation) or on concrete retaining walls.​

As with any other surface, you will need to ensure the retaining wall is in good condition. If you render over a retaining wall that is falling apart, the render will not hold up well and will be easily damaged.​

Best Render Types for Retaining Walls in Sydney

Not all render types work well on retaining walls. You will need to choose a render type that works well with exposure to the elements and ground pressure.

​Cement Render – The Best All-Rounder​

For most retaining walls, cement render is the go-to option. It’s strong, holds up well in outdoor conditions, and produces a clean, elegant-looking surface that you can paint any colour you like. It’s also the most cost-effective option.

The most important thing to keep in mind with cement render is that it needs to be painted. Raw cement render will absorb moisture and stain over time if it is left unpainted. A quality exterior masonry paint adds both protection and colour.​

Acrylic Render – Great for a Coloured Finish

Acrylic render has colour pigment mixed in, so you get a finished, coloured surface without spending extra time or money on paint. It is  slightly more flexible than cement render, which gives it better crack resistance, making it ideal for retaining walls.​

Silicone Render – Best for Pools Or Coastal Areas

If your retaining wall is near a pool, in a low-lying area that retains moisture, or in a beachside suburb where salt air is a factor, silicone render is a great option. It’s the most water-resistant render option and handles moisture exposure very well.​

How to Render a Retaining Wall

Here are the essential steps to follow when rendering a retaining wall:​

• Assess the wall: Check for any structural or water damage, signs of mould or stains. The render will not bond well with a damaged retaining wall.
• Clean the surface thoroughly: Remove any dirt, algae, mould, efflorescence (white salt deposits), and any debris. A pressure wash is usually best for concrete block walls. Wait for the surface to dry fully.
• Repair any cracks: Fill any small cracks or holes. This provides the render with a stable surface to bond to and prevents moisture from entering from behind.
• Apply bonding agent or primer: A bonding agent or primer improves render adhesion.
• Apply the scratch coat (base coat): The first coat of render is applied, then scratched with a comb-like tool to create a rough surface for the finish coat to grip. Ensure your base coat dries and cures before applying the next layer of render.
• Apply the finish coat: The final coat is applied to the desired thickness and completed with the desired finish (smooth trowel, sand texture, paint or rough texture).
• Cure the render properly: Newly applied render needs to be kept slightly damp for the first 48–72 hours to prevent it from drying too fast and cracking.
• Paint or seal (if using cement render): Once the render has fully cured (around 28 days for full strength), apply a quality exterior masonry paint or sealer to protect the surface and finalise its look with an elegant neutral colour or a stylish bright colour that stands out and draws the eye to it.

What Impacts the Cost of Rendering a Retaining Wall?​

• Wall height and access: Taller walls or those in tight spaces take longer to render and may require scaffolding to access and render them.
• Surface condition: Retaining walls with significant cracking, old failing render, or moisture damage require additional preparation before rendering can begin; otherwise, the render will not last long.
• Render type: Some render types are more expensive than others. Cement render is the most affordable, while acrylic is in the middle range, and silicone is the most pricey.
• Finish type: A smooth, polished finish takes more skill and time than a sand or texture finish.

Mistakes to Avoid When Rendering a Retaining Wall

Rendering Over a Damaged Retaining Wall​

Render will crack and fall away quickly if the wall beneath it is damaged or not cleaned properly.​

Skipping the Bonding Agent On Smooth Surfaces.​

Rendering a smooth concrete wall without a bonding agent will result in poor adhesion, and the render is likely to come loose and peel.​

Not Keeping the Weeping Holes Clear

Retaining walls require small holes, known as weep holes, to relieve water pressure behind them. Rendering over or covering weep holes traps moisture, leading to render failure.​

Rendering in Hot Or Dry Conditions without Misting​

Hot weather can cause render to dry too quickly on retaining walls exposed to the sun. If a render dries too quickly, it can cause shrinkage and cracks. Keep the surface damp during curing time.​

Not Sealing Or Painting the Cement Render​

Using raw cement render on a retaining wall will absorb water, promote mould growth, and stain over time. Always finish a cement render with a quality exterior masonry paint or sealer.​

At Sydney Cement Rendering, we take pride in being Sydney’s trusted rendering experts. From residential jobs to large-scale commercial projects, we provide our customers with the highest-quality rendering services and adapt to every situation and rendering style. To learn more about rendering a retaining wall and to get an accurate quote, give us a call at 0402 704 984 or visit our website  https://sydneycementrendering.com/ to find out more about the services we offer!

FAQs

What is the Best Render for a Retaining Wall in Sydney?

Cement render is the most popular choice, due to its durability, cost-effectiveness, and versatile finishes. Acrylic render is a good option if you want a built-in colour finish without painting the wall separately. For walls near pools or in Sydney’s coastal suburbs, silicone render offers better long-term moisture resistance.

How Much Does it Cost to Render a Retaining Wall in Sydney?

As a rough guide, rendering a retaining wall in Sydney costs between $35 and $90 per square metre, depending on the render type and the retaining wall’s condition. A small 15 m² wall might cost anywhere from $500–$1,200 in total.

Please note that all these prices are rough estimates only. Your actual quote will depend on multiple factors. Contact Sydney Cement Rendering to get a better idea of the costs involved.

Do I Need Council Approval to Render a Retaining Wall in Sydney?

Rendering a retaining wall does not usually require council approval. However, if you are building a new retaining wall over 600 mm in height, council approval may be required, depending on your local council and the location of the wall.

Always check with your local council if you are building from scratch.

Can I Render a Retaining Wall Myself?

Rendering a retaining wall is usually a fairly straightforward DIY job with the right materials and instructions. However, rendering a large, damaged retaining wall with moisture issues or that requires scaffolding is best left to a professional. Poor preparation or application of a retaining wall is a common cause of the render failing within a few years.

Does the Soil Side of a Retaining Wall Need Waterproofing Before Rendering the Front?

In most cases, yes, especially for taller walls, walls in low-lying areas, or walls that retain a large volume of soil. Applying a waterproofing primer to the soil side before rendering the wall reduces moisture pressure behind the render and significantly extends its lifespan.​

If you’re unsure whether your retaining wall needs waterproofing, ask Sydney Cement Rendering for advice.