Insulating concrete formwork (ICF) is a building system that uses lightweight formwork (made from an insulating material) to support concrete walls whilst they are being cast in-situ and which is then left in place as insulation.
Used on the continent and in North America for many years, ICF has proved to be robust, cost effective method of constructing of variety of building types – from houses and basements to multi-storey cinemas and commercial buildings.
How is it used in practice?
Insulated concrete formwork consists of twin-walled expanded polystyrene panels that are stacked together to create the permanent formwork used to contain the ready-mixed concrete for the walls.
The insulated formwork remains in place to provide complete thermal insulation to the walls of the finished building. It also provides a uniform surface ready for direct application of most finishes and proprietary cladding systems. Many insulated concrete formwork systems also incorporate their own flooring system.
- The blocks that make up the insulating formwork are manufactured in a variety of shapes and component types, creating limitless design opportunities. For example, features such as bay windows and arches can be generated without having to resort to specialist products. In addition, floors can be constructed using ICF components.
- Any type of foundation, flooring, partition, stair or roofing system is compatible with ICF construction.
- ICF provides an easy means of achieving high standards of structural, energy, fire and acoustic performance.
- The exterior of the building can be clad in any finish the architect requires including masonry, brick slips, render tiles, curtain walling and weather boarding. Internally, plaster or dry lining is applied directly to the face of the expanded polystyrene formwork.
ICF advantages for the builder:
- ICF is quick and easy to use without the need of skilled tradesman. In fact, any builder can quickly erect an ICF structure since the lightweight units are easier to handle than traditional materials. Typically an experienced team of four can erect and concrete the walls of a three-bedroomed bungalow in a day, significantly reducing the contract program.
- The low labour and reduced need for skilled tradesman result in more efficient use of increasingly scarce construction workers. Also, with the speedy construction of watertight building envelope, internal services and finishings can progress independently of external cladding.
- Service ducts and utilities can be pre-installed within the concrete core or chased into the expanded polystyrene using a router of hot-wire cutter.
- ICF components and temporary bracing systems are delivered as lightweight portable packs, which do not require mechanical handling or the use of special tools.
- Just-in-time deliveries and direct placement of ready-mixed concrete reduces waste and site storage facilities. Also, the energy-efficient building allows downsizing of the boiler.
ICF Advantages for the occupier
- The occupants benefit from low running expenses, as the energy-efficient building costs less to heat. In fact, some houses need no heating other than that provided by solar energy.
- The ICF insulation reduces impact sound, while the concrete core provides a solid mass to reduce airborne noise. This makes the system ideal for party wall construction.
- All ICF materials are inert, giving no toxic fumes. Also, the building maintains an even comfortable temperature, and air quality is essentially controlled – good news for those with asthma or other allergies. There are no problems with condensation, mould or mildew.
- All expanded expanded polystyrene materials used in ICF buildings are treated with fire retardant, thus giving all ICF systems appropriate fire certifications. All mortgage lenders, insurance companies and planning authorities accept ICF certification.
Article by: Jamshaid Sawab