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As demand for super-insulated and airtight building structures grows, insulating concrete formwork is rapidly gaining popularity as a method of building construction. Building with Insulated Concrete Forms is a proven way of creating an eco-friendly, stronger, safer building that's highly energy efficient, needs minimal maintenance and repair; and one where design possibilities are limitless.

It's a modern fast-track method of construction suitable for commercial, residential, industrial, institutional, healthcare and a variety of other building types. Insulated concrete formwork (ICF) is an in-situ concrete system of building that is quick to construct and offers superior levels of performance over alternative methods of building envelope construction

ICFs provide a simple yet effective method of constructing durable, energy-efficient buildings quickly and cost-effectively. They allow the specifier to create a wide variety of designs with curves, arches, complicated, intricate patterns and varying angles. ICF has its own logic and methodology, which when correctly applied produces excellent buildability and flexibility. The simplicity of the system makes it inherently adaptable and changes to the formwork can be incorporated into the design up until the concrete is poured on site.

Insulating Concrete Formwork method of building construction uses hollow lightweight block components that lock together without intermediate bedding materials, such as mortar, to provide a formwork system into which concrete is poured.  The blocks are formed of panels of insulation material, usually expanded polystyrene (EPS) or extruded polystyrene (XPS), tied together with plastic or steel ties. As with in-situ formed concrete walls and floors, reinforcing steel bars are usually placed inside the forms before concrete is poured to give the predominantly concrete structure flexural strength and to reduce cracking. Once the concrete has cured, it becomes a high strength concrete frame structure with the formwork remaining in place to act as insulation.

ICF forms have to be filled in a more controlled manner, to aid in managing the weight and pressure brought to bear on the polystyrene blocks. When placing concrete within the ICF units, there is a potential for damage to occur, both from pouring heavy, viscous concrete into a relatively fragile structure and when vibrating and compacting the concrete sufficiently. Careful placing and compaction of the concrete is required to minimise damage, along with adequate propping of the ICF structure prior to pouring the concrete. It is sometimes difficult to determine if this has been done well enough to release all the trapped air from the mix and to avoid honeycombing within the concrete due to poor compaction/vibration. One way of addressing this problem would be to use selfcompacting concrete – although there would be cost implications.

Upper and lower surfaces of the polystyrene panels are castellated and the vertical mating surfaces are tongue-and-groove to form a tight fit when joined together. The rigid formwork does not require supporting falsework. The inner surfaces have tapered grooves running vertically and have offset on opposite faces to ensure uniform concrete thickness. They also form locks for end stops. The outer surfaces are grooved vertically at specific centres to aid cutting and trimming.

Standard core thicknesses comprise 102mm, 152mm, 203mm, 254mm and 300mm, although thicker cores are also achievable. Inherently flexible and design-orientated, ICF is able to accommodate 90- and 45-degree corners, brick corbel forms, brick corbel extensions, T-form units, double-taper top forms and factory-cut radius forms.

ICF has proved to be robust, cost effective method of constructing of variety of building types – from houses and basements to multi-storey and commercial buildings. The insulated formwork that remains in place provides 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. 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.

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. Many insulated concrete formwork systems also incorporate their own flooring system.

Any type of foundation, flooring, partition, stair or roofing system is compatible with ICF construction. The ability to use a range of roofing, flooring, utilities and opening systems allows the designer total freedom to choose their preferred supporting non- structural building components. Most ICF systems have compatible flooring systems which can be poured at the same time as the supporting walls.

ICF walls are constructed one row at a time, usually starting at the corners and working toward the middle of the walls. End blocks are then cut to fit so as to waste the least material possible. As the wall rises, blocks are staggered to avoid long vertical seams that can weaken the polystyrene formwork. Structure frames known as bucks are placed around openings to give added strength to the openings and to serve as attachment points for windows and doors.

ICF decking can also be designed in conjunction with ICF walls to form a continuous monolithic structure joined together by rebar. ICF decking is becoming an increasingly popular addition to general ICF wall construction. ICF decking weighs up to 40% less than standard concrete flooring and provides superior insulation. ICF deck roofs are popular in storm-areas but it is harder to build complex roof shapes.

Insulating concrete forms systems can vary in their design. "Flat" systems yield a continuous thickness of concrete, like a conventionally poured wall. The wall produced by "grid" systems has a waffle pattern where the concrete is thicker at some points than others. "Post and beam" systems have just that – discrete horizontal and vertical columns of concrete that are completely encapsulated in foam insulation. Whatever their differences, all major ICF systems are engineer-designed, code-accepted, and field-proven.