FAQ’S

Do you have a question about Gabion Walls? Here are the answers to some of the most commonly asked questions.
Feel free to get in touch, we're more than happy to help.

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How do I calculate how much rock I need for my Gabion Basket?

The best way to calculate how much rock you will need is to calculate the area of the basket. Do this by multiplying the length by the height by the depth. For example: How much rock do I need if my gabion basket package is 5m long, 1m high x 0.5m deep?

5m x 1m x 0.5m = 2.5 cubic metres of rock.

Landscape supply yards and other rock supplies will generally sell rock in the cubic metre (m3). Often 1 bucket load from their loader is 1m3 so this makes it easy to determine the correct cubic meterage required.  We've helped save you time by calculating the rock required for a range of common sized baskets.  Simply multiply the value by your wall length to get your total cubic metre rock required.  See the table here

What rock size can I use?

This is important to ensure your rock doesn’t fall through the aperture (mesh opening) of the basket. Using our 50x50mm mesh means your rock size can be smaller than using a larger mesh of 75x75mm or 100x50mm. The challenge with larger mesh is that you require larger rock which can often create large gaps between the rock. This exposes more openings and within the basket which is aesthetically displeasing.

The mesh opening is 50x50mm. This means that any rock smaller than 45mm or 50mm in diameter will fall through the wire mesh. Based on the aperture above, the recommended rock size is a minimum of 70mm stone. Normal size rock would be 70-150mm

How do I build my Gabion?
Building a gabion basket is very simple. If you are building one for the first time, allow up to 15 mins to put it together. If you're building more than one, you will be able to put a basket together in 8-10 mins with some practice.   Take a look at the indepth guide on how a basket comes together here or watch the video
What is the difference between a Galfan and Galvanised finish?

We offer both a galvanized or a galfan coating on all our range. Both coatings are widely accepted globally as suitable coatings for corrosion resistance in outdoor applications.

Galvanised steel products have been around for hundreds of years. The process of galvanising is believed to have been discovered in India in the 4th century AD and was later discovered by Europeans in the 17th century when it had been used as armour for Indian armies. These days, galvanised steel is everywhere. Most commonly used in the construction industry, galvanised products include support beams, piping, heating and air conditioning duct work, barriers and handrails. Galvanized steel is used to make outdoor grates used for industrial walkways street lights, beds, washtubs, buckets, nails, planter boxes and of course, gabion baskets.

Galvanisation is the process of applying a protective zinc coating to steel, to prevent rusting. The most common method is hot-dip galvanizing, in which parts are submerged in a bath of molten zinc. Galvanizing protects in two ways.

  • It forms a coating of corrosion-resistant zinc which prevents corrosive substances from reaching the more delicate part of the metal.
  • The zinc serves as a sacrificial anode so that even if the coating is scratched, the exposed steel will still be protected by the remaining zinc.

Source: Wikipedia

Galfan is zinc-aluminum alloy coating as compared to a pure zinc coating (galvanized). It is generally 95% zinc, with 5% aluminum alloy and mischmetal steel. Galfan offers an excellent level of protection against long term corrosion as the corrosion rate is closer to a parabolic shape rather than linear as per a galvanized finish.

The type of finish most recommended is dependent on the location and expected life span of the project.

Why is mesh size important?

If you're going to the effort of building a retaining wall, feature wall, water feature or even letterbox using a rock filled gabion basket, you want to know it's going to last. After all, this is going to be a feature of your outdoor area and if you're going to do it, you might as well do it right.

One of the most basic but crucial aspects of your gabion basket is making sure the rock / stone you are going to fill it with, actually stays in the basket. Here's what I mean: The baskets by design are a steel mesh in grid form, therefore there are consistent gaps between the steel cross beams. The gaps between the mesh wire of the gabion basket is called it's aperture.

The gap between the steel cross beams of wire mesh vary from manufacturer to manufacturer in both shapes and sizes. Some manufacturers promote the use of chicken wire style. There are 2 problems with this:

  • They don't look very good. Don't believe me? - read more on this here.
  • The poor quality of the low gauge steel can compromise the structural quality of the application

The thin, low gauge steel wire is very easy to move and bend. This means is that rock filling can manoeuvre the wire. Alarm bells should be going off for you right now. The rock filling can manoeuvre the wire! This means the rock inside the basket can move, stretching the wire, creating weak spots and ultimately creating an inconsistent aperture throughout the basket. An inconsistent aperture now means that there is potential for rock filling to start spilling out of the basket. What a disaster...

The alternative is a strong, high gauge (4 or 5mm) steel basket with a consistent, square aperture. This is what we offer at Gabion Walls Australia.

How do I fill my Gabion with Rock?

One of the most critical aspects of installing a gabion retaining wall, rock wall or landscape feature is ensuring the rock filling is packed inside the basket as effectively as possible.

Different types of rock filling requires slightly different techniques. For example, stone of a flatish nature will pack to a denser finish than rounded pebbles or river rocks. Flatter stones will give you a traditional dry stacked effect in your basket as opposed to a rounded river rock that will which will give a more freeform jumbled look.

If using a river rock or rounded stone ensure that the stones are placed and stable before continuing on to the next layer, rounded stones tend to compress under weight (as they are only touching each other at a few points) and you could end up with some bellowing out at the centre points. This will often happen if you just pour the stones in.

Sedimentary stone, like Castlemaine Stone, tend to have grains or layers within them, this allows for splitting or fracturing to give a flatter surface and therefore greater areas of contact between stones. This allows for smaller gaps and a denser finish to the wall of the gabion basket. Once placed into position there is very little chance for movement of the stone.

Watch the video on installing rock in your gabion basket

What foundations do I need for my Gabion Wall?

If the gabion wall height is up to 1m, a base of crushed rock should be adequate to a depth of 100mm compacted. This would generally apply for both retaining and free standing.

If the wall is more than 1m high:

  • Free standing will in just about all cases need a concrete footing, of which width and depth would need to assessed against the height of the wall. This is best determined in consultation with a certified engineer.
  • Retaining wall requirements will also vary, with most still able to use crushed rock, but once again consultation with an engineer to determine what depth etc, due to varying conditions such as payload against the wall, soil conditions etc...

Each wall, site and design is different so consult a structural engineer for more information.

How do I fit the bracing wires?
Bracing wire (also known as spreader bars) are required to hold the welded wire mesh panels in position as you fill the baskets. As the baskets are filled the rock tries to push the mesh out. The bracing wire holds the mesh into position to avoid this.
Do I require a permit for a Gabion Retaining Wall?

Permit rules are domain of local councils and often change from council to council and state to state.

VIC
In Victoria any retaining wall less than 1m in height is exempt from a building permit unless it is associated with other building work or with protection of an adjoining property.

Please check with your local council for specific requirements and the Victorian Building Authority for more information:

https://www.vba.vic.gov.au/__data/assets/pdf_file/0008/99377/435e072fb618d1705631474c9b0b90e67b72c4df.pdf


NSW

Generally in NSW you do not need council approval if your retaining wall is:

  • less than 600 mm above or below ground level
  • at least one metre from any boundary line, easement, sewer or water mains
  • separated from other retaining walls on the property by a minimum of 2 metres

Please check with your local council for specific requirements and the NSW governing body for more information:

https://www.lawaccess.nsw.gov.au/Pages/representing/lawassist_fences/retaining_walls/approval.aspx


QLD
In Queensland, building regulations advise you will not need building approval for a retaining wall if:

  • There is no 'surcharge loading' over the 'zone of influence' for the wall
  • The total height of the wall is less than 1 metre above the wall's natural ground surface
  • The wall is no closer than 1.5 metres to a building or another retaining wall
  • The wall does not form part of the fencing for a pool.

Please check with your local council for specific requirements and the NSW governing body for more information:

https://www.brisbane.qld.gov.au/planning-and-building/do-i-need-approval/residential-projects/yards-pools-fences-and-landscaping/build-a-retaining-wall

How high can I build my Gabion Retaining Wall?

Understanding the rules and regulations of building retraining walls using gabion baskets in Australia can be tricky, confusing and costly if you don't get it right. It's important to know what needs to be done to make sure your retaining wall is in line with regulations yet still performs it's function with the look you want..

For further information on tips and ideas for gabion baskets used in rock retaining walls, check out Gabion Baskets for Rock Retaining Walls.

What is the life span of a Gabion Basket?

Gabion baskets are designed to last an a long time in outdoor, adverse conditions. The rate at which the gabion basket will corrode is dependent on a large number of factors including:

  • Project and site conditions
  • Corrosivity atmosphere conditions
  • How much time the basket is covered in a corrosive liquid
  • How much exposure to airborne salt the basket will be exposed to
  • Industrial pollutants and chemical attack
  • Shelter from rain and regular washing
  • Chemical makeup of soil content
  • Wire size – while corroding at the same rate, thinner gauge wire will fail before thicker gauge wire.

The Atmospheric Corrosivity Zones in Australia (AS 4312:2019) defines 6 categories of corrosivity:

Category Corrosivity Typical Environment Expected Life Span
C1 Very Low Dry Indoors 100+ years
C2 Low Arid / Urban inland 100+ years
C3 Medium Coastal / Light industrial 50+ years
C4 High Seashore (calm) 30+ years
C5 Very High Seashore (surf) 15+ years
CX Extreme Shoreline (severe surf) 5+ years
How do Gabion Baskets compare with Timber Sleepers?

The nature of timber is that it will rot over time. How long it will endure can vary due to factors such as moisture, pine versus hard wood, drainage behind the wall, etc. As well as rotting by natural causes, they can also degrade with infestations of termites.

Gabions are manufactured to survive for decades in most environments in Australia, with a 60+ years lifespan.

What do I get with My Gabion Basket flatpack?

Once you have decided what size gabion basket you need to complete your retaining wall, rock wall or landscape masterpiece, you have the option of picking it up or delivered. All baskets are available in flat pack form or pre-assembled.

Pre-assembled baskets save time for a quick installation however the flat pack form and building yourself is easy and the most cost effective solution. As the gabions are so easy to put together, our recommendation is to build and place in final resting location when on site.

Approximately 40 baskets can be stacked in flatpack form on a single pallet (totalling approximately 1m high). As you can expect, this is more effective way of transporting the baskets compared to picking them up pre-built due to sheer shipping volume.