Getting gabion wall design right can be tricky and if you are wondering how to build one, you are certainly not alone. Over the past five years, our practice has seen an explosion in the use of gabions within residential projects, where once they were a more common sight in commercial applications.
I think the rise in the popularity of gabions in terms of garden wall ideas is mostly down to their versatility, relatively low cost and the fact that they are fairly easy to install. So how are they used in domestic construction?
Here, we take a look at exactly what a gabion wall is, where they can come in handy and how to design and build one.
What is a gabion wall?
At its simplest, a gabion wall (from the Italian term gabbione meaning ‘big cage’) is a modular containment system — typically referred to as a cage or basket — made from a wire mesh and filled with rock. The cage element is constructed most commonly as a square, rectangular or trapezoidal.
Are there different types of gabion retaining wall?
There are two main types of gabion wall construction — those built to meet the retaining wall ideas of those after something for structural purposes and those built for shallower retaining walls that only need to hold back a very small amount of soil. Gabions can also be used for decorative landscaping, too.
Here we take a look at the various different types of gabion walls and how they are constructed.
Which gabion wall design is best for gardens?
Walls that are only retaining a small amount of garden ground (i.e. 1m and below), can be laid in one row and linked with lacing wire.
Because there is a lot less ground to retain, the specification and therefore cost and complexity of installing a gabion wall is significantly decreased. There are also more options to use any type of stone, as this is more of a decorative application.
Other decorative applications for gabion walls include raised flower beds and planters, tables and patio seating, internal feature walls, privacy screening or as fencing and hard landscaping.
Which gabion wall design is right for me?
This all depends on the style of your house and the kind of garden you have, or are trying to create — those after sunken garden ideas very often use gabion walls in the design.
Aesthetically, the filled cages provide a raw, natural and rustic structure that can be left exposed to show the rock in situ. Ideally the type, colour and size of the rock will be matched to the colour palette of the main house or as part of a wider hard and soft landscaping scheme.
You can also change the look of the wall configuration by going from a battered sloping wall to a stepped-back front. A battered retaining wall will lean back towards the surface it is retaining — this can be done by slightly staggering or leaning the cages. A stepped retaining wall is easier to build as you’re simply stacking cages on top of each other at a larger distance. A battered wall has more retaining capacity than stepped.
How do you build structural retaining gabion walls?
The original use for gabions is in large civil construction projects as gravity retaining walls, such as at the side of a motorway, retaining the sloping banking above.They can be used domestically when building a house into a sloping site, for example.
In this application numerous cages are laid side by side and stacked up (in an overlapping layout), these are internally braced and laced together. They are filled with angular stones with known structural properties, compacted and then back filled with suitable infill material, such as a well-graded granular material.
Note that as the height of the wall increases, the foundation depth also has to increase, so a wall as high as 5m may be as deep as 2.8m at its base. To aid stability the walls are usually sloped backwards at 6–10 degrees from the vertical. If you are opting for a structural retaining wall, you must inform a structural or civil engineer, who will review soil investigation studies and design the retaining wall to suit
the bearing capacity of the ground and the stability of the slope being retained.
Engineers will design a gabion retaining wall with similar principles used in concrete block walls. However, gabion walls need much more volume to make up the difference between the mass of stone versus concrete.
As discussed, the height of the wall and stability of the ground that is being retained is vital in your calculations. In addition, the location, and exposure will impact the size and type of wire used in the basket. Typically, these come in 3mm, 4mm and 5mm gauges, with the larger being used for coastal locations and civil structures.
The material needed to fill a structural gabion should be:
- Hard, durable, and non-degradable stone
- Free draining
- Ideally 100-200mm diameter
- Angular stone, preferably, to limit movement
- The exposed surfaces should be hand-packed.
Is a DIY gabion wall a good idea?
When used as a decorative or non-structural feature, it is fine for homeowners to buy the baskets and infill stones, then complete the install themselves. Most suppliers will provide enough information for competent DIYers to follow.
However, if the gabion is being used to retain more than 1m of soil, then I would suggest leaving this to a groundworks contractor.
If you’re uncertain about ground conditions, please seek the advice of an engineer before starting.
All is a chartered architect who has overseen the design of over 450 low-energy homes.
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Allan is a RIBA chartered architect and has overseen the design of over 350 low energy homes across the UK. He is one of the UK's leading experts on modern methods of construction including SIPs (structural insulated panels), is part of the Structural Timber Association, Passive House Trust and a member of the self build industry body, NaCSBA. He regularly contributes to Homebuilding & Renovating magazine and is a speaker and self build expert at the Homebuilding & Renovating Shows. Since 2009, Allan has grown his custom and self build architectural practice, AC Architects, to a team of 16, and recently created AC Structures, a leading engineering business for self build projects.