Gabion Wall Frequently Asked Questions
What Are Gabions?
Gabions are wire mesh containers constructed from galfan coated steel, filled with hard rock, stone or other materials including reclaimed and recycled aggregates.
Gabions are made up from various sized panels which are formed up into a box. The panels are connected together with either spiral / helical wire or with C-Rings applied by pneumatic hand tool.
Gabion walls are considered a gravity wall system.
Gravity walls depend on their own mass or weight to withstand pressures from behind the structure, in this case weight (rock) held within the gabion container.
The containers are linked together when assembled which creates an individual structure. Once the gabions are linked the strength of the structure increases significantly. This allows the user to form walls for retaining land, eliminate erosion, control water speed, support river banks and many other applications.
Gabion walls are popular in modern day landcape designs because they look fantastic, offer longevity, zero maintenance, eliminates drainage pressures plus they are cheap to install and are able to withstand significant pressures without deforming due to their flexibility.
Gabions have become popular as architectural features such as seating, cladding, pylons, feature walls, planter boxes and more.
Are Gabions Cost Effective
Gabions are considered a cost-effective solution to most situations. There are 2 main gabion types being woven diamond wire typically used in large scale civil projects (less expensive) and weld mesh type cages, made from 4mm welded panels commonly used for landscape and architectural applications where longevity and high aesthetics are important.
Century Gabions are weld mesh design, typically used by engineers, landscapers, architects and DIY users for their superior form and functionality.
What Type Of Rocks Do I Use?
For most gabion projects the recommended rock fill size range is between 75mm-150mm.
Generally a basalt rock would be used to fill gabions. Basalt is hard and durable, capable of withstanding weight loads typical with gabion structures.
For smaller non structural gabion projects, try using other types of rock or stone based on colour, texture or availability.
We suggest getting in touch with your local landscape yard or quarry to discuss suitability and availability based on geographic location.
How Long Do Gabions Last?
As noted above there are two types of gabion basket construction, woven and welded. Woven baskets are manufactured with 2.7mm wire while weld mesh gabions are manufactured with 4mm wire.
Woven baskets are less expensive however provide less life cycle.
The origin (country of manufacture) and coating type also plays a significant part in the life span of gabions. As an example low cost gabions from China have much lower steel strength and low quality coating type and density.
Galvanised gabions may last from 5 to 10 years. where as Century Gabions with galfan coating will last anywhere from 50-100 years .
Galvanise
Galvanise coated wire is typically used in fencing and general purpose applications in Australia.
Galvanise coating works fine in light duty applications however does not meet industry standards for gabion structures. Effectively the galvanised coating has a short life cycle and this could prove catastrophic if the mesh panels fails after construction.
Tests have proven material which originates from China. shows significant corrosion after a short period of time and weld points were weak, in fact could be popped off the cross wire with little pressure.
Reports from engineers have been similar, in some instances gabion structures constructed with non compliant gabions have been removed from project sites for safety reasons.
If the material is imported from China it simply will not conform to Australian / International standards.
Our motto is : ” The Cost Of Replacement Is Far Greater Than Doing It Correctly First Time Round”.
If your unsure about quality while shopping around – request a manufacturers data sheet or mill data sheet.
There are numerous websites making false claims about quality and longevity of their mesh as being compliant to Australian Standards, we have learned that most are cheap imported galvanised fence panels.
Century Mesh & Century Gabions not only meets Australian standards but far exceeds them and we maintain direct relationships with the manufacturers for data sheets and certifications.
The below image shows rapid corrosion of galvanised mesh used in gabion wall. This corrosion was present in 3 years after installation.
Tech Guide | What Is Galfan Coating
Another mis conception is wire diameter. The industry standard is 4mm.
In short Century Gabions have higher tensile strength, weld strength and shear strength than any other mesh on the market for gabions. Couple this with genuine galfan coating and 50×100 aperture and now we’re talking the highest spec batch manufactured mesh in Australia.
A 5mm option will only offer benefit provided it’s manufactured to the same spec as Century Mesh.
Most providers of 5mm gabions typically fall back under the umbrella of Chinese mesh. The increased diameter therefore offers no advantage.
The mesh remains very low carbon steel, low tensile strength, low shear strength, weak weld points and questionable coating type and coating density.
The below image shows 4mm galfan coated wire versus 5mm galvanised wire. Both items were tested in tidal water side by side, same length of time, at the same location. The galvanised mesh shows significant corrosion
Tech Guide | What Is Galfan Coating
Do Gabions Need Foundations?
Gabions are most commonly laid onto compact road base so the gabion wall is fully supported. For most gabion wall projects 100mm depth of road base would be sufficient.
Where gabions are used to create a retaining wall 2-3 metres high or higher, its recommend the baskets are laid at a batter angle (leaning back) of around 6-10 degrees.
You can create this batter angle by using the base gravel. Its recommended the assembled gabions are placed onto the aggregate and checked for alignment before filling them with rock.
Another option is staggering or stepping them back, this step back could be anywhere from 300mm to 1m depending on project demands. An engineer should be consulted for design and construction plans where appropriate.
With increased popularity gabion fences and pylons are generally built on top of a concrete slab with internal steel posts running through the centre of the gabion for extra stability.
As most fences are low profile, say 300-500 depth with height of 2 metres the internal weight is to great for the gabion structure to be considered freestanding therefore the structure requires additional support internally.
As a guide a 2 to 1 ratio applies.
If the gabion structure is retaining earth at 1m high the depth of the gabion needs to be 500mm.
As the height of the gabion increases, it may be possible to step the gabions back and possibly decrease the depth of the wall.
Another option is terracing the gabion wall. The structure can be built to a certain height and depth (using the 2:1 ratio) then leaving sufficient space, say 1-2metres between the top of the first gabion structure and the base of the second gabion structure.
Do Gabion Walls Require Planning Permission?
Consult your local council for height guidlines, in most states in Australia a wall can be constructed to 1 metre height without requiring council or engineering.
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