Derived from the Italian word for “big cage”, gabions are wire mesh manufactured boxes that are filled predominately with a grade 6G (100 to 150mm) aggregate that are used for mass gravity retaining walls within civil engineering applications. In recent years their use for Architectural applications such as claddings, rain screens and free standing walls has increased significantly. The UK’s leading mesh wall company Enviromesh, founded by Roger Farmer and Neil Holmes who jointly developed the Gabion 27 System, recently supplied these specially formatted cladding units and fixing arrangements with great success for Crest Nicholson’s eco-development, ICON in Street, Somerset. Here, the retaining walls form part of a green design approach that has resulted in energy-efficient homes offering affordability with significantly cheaper running costs. As an example of this, the average annual cost of heating a home at ICON is just £190 compared with £900 for a typical Victorian property.
The stone used to fill the system was sourced locally helping to reduce transport emissions and cost. Increased durability was another important factor, hence the mesh was Galfan coated (95% Zn/5%Al) to ensure a design life of up to 70 years was achieved with little maintenance. The bespoke wall cladding units are based on the Gabion 27 system format and measure 2.06m long and 2.06m high. This specially formatted system 305mm wide, was manufactured with 4mm wire diameter front and rear panels and 3mm wire diameter side and diaphragm panels all corrosion protected. The success of the aesthetics of this scheme has led to a further order for an adjacent building which is currently under construction.
Retaining walls made easy with the Gabion 27 System
The key benefits of this system for retaining wall applications are:
- High-quality design contrasted by reduced wall section in comparison to conventional systems
- Better distribution of internal mesh reinforcement within the wall
- Improved aesthetics due to internal reduced cell size
- Easier installation through the smaller modular size
The system offers several advantages compared to conventional solutions. For example, deformation is reduced, thanks to the adoption of heavier mesh wires on the exposed visual surfaces. Furthermore, specially designed internal preformed ties have been developed not only to assist with the installation of the product but also to improve wall alignment and aesthetics, this being of particular importance in architectural applications.
The system offers a number of benefits helping contactors with the construction:
- Steel helicals for all vertical connections, providing the strongest and most consistent joint
- Extended bases that form the lids of the units beneath, reducing installation time and steel content
- Ability to incorporate stepped or flush-faces on the wall
- Supply of preformed trapezoidal corner panels with a 10˚ taper that provide clean-looking corners
- Reduced unit heights of 686mm that simplify the entire process of hand placing the internal aggregate.
In addition to the dimensionally stable welded mesh panels that form the gabion, all of the steel wire accessories are also Galfan coated ensuring the system’s integrity and durability exceed that of traditional pure zinc galvanising.
The reduced wall section size also means that less fill material is needed, less excavation is needed and of course the foundation strips can be narrower. At the Crest Nicholson project, sustainability is also an important factor, with timber, stone and bricks sourced from the local area. Waste materials have been recycled wherever possible and all displaced earth is re-used to reduce waste transport to landfill sites.
Andy Goodman of Capstan Contractors Ltd commented: “The Enviromesh product was tailor-made for our application of a concrete-framed block of apartments with a car park undercroft. The system was delivered in flat lightweight sheets and assembled in-situ, which made it easy to handle with a little requirement for storage. Owing to its simplicity, just one trade was needed to install it. As the site requirement for aesthetics was high, we used a stonemason for the stone fill and had the system filled as though it were a dry stone wall. The gabion wall construction process is straight forward and although Capstan assembled the kit, it could be done by anyone working from the simple drawing supplied by Enviromesh. No wet trades were required, so less time and money was needed and less mess created than if we used conventional walling systems yet it looks natural and allows ventilation while keeping out the water…ideal for a car park.”