ICF – the concrete choice for true building performance

Jean-Marc Bouvier, UK technical manager for Insulated Concrete Form (ICF) manufacturer NUDURA, talks about how this proven building envelope technology offers a fast-track, economical and sustainable solution that’s built to last.

Building with Insulated Concrete Forms (ICF) 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 method of construction suitable for commercial, residential, industrial, institutional, healthcare and a variety of other building types.

Switching from traditional building methods to ICF technology will significantly reduce labour and increase speed of build. ICF offers considerable benefits over both brick and block and timber frame.

But what is an ICF? The forms consist of two stay-in-place panels of expanded polystyrene. The best engineered systems are connected with an innovative folding web which minimises wastage and offers greatest flexibility. The forms are transported flat to site, opened and stacked, reinforcement placed, propped and then filled with concrete, creating a solid monolithic con- crete wall for above and below ground applications.

ICFs offer great durability and strength; for example, a 15cm core wall can be designed to heights up to 4.3m within a single storey. ICF structures have been built up to 25 storeys in height, making them ideal for hotels and skyscrapers.

Six building steps are completed within one product: form and wall structure, insulation, air and vapour barriers, and the interior and exterior finish anchorage.

So ICFs are the perfect partner to fast track construction programmes and the savings in terms of time and labour speak for themselves. The largest and most advanced ICFs available make building measurably easier and faster. Building in traditional brick and block, a wall 2.75m high x 7.3m long without openings would typically be erected by three men in 16 hours with a total labour time of 48 hours.

Using ICF technology, the same wall can be erected and poured in five hours by two men utilising only 10 hours’ labour, so there’s almost an 80 per cent saving on labour costs. The best ICFs are 50 per cent faster than concrete cavity construction and require as low as 0.5 man-hours/m².

Size does matter and premier products are typically larger than standard systems. They consist of two panels up to 70 mm in thickness and are connected together by an industry-leading interlocking web design. Site waste is 50 per cent less than cavity block and when compared to other ICFs, this system offers waste levels as low as one per cent, thanks to a four-way reversible design. When the form is able to be folded, this reduces installations times, increases transport capacity by up to 40 per cent and decreases the amount of space required for on-site storage.

The main benefits explained

Energy efficiency: ICF structures greatly reduce air infiltration, which optimises energy performance and offer excellent thermal bridging values. The best forms on the market, when combined with the structural strength and thermal mass of con- crete, can provide U-values as low 0.11, meeting and exceeding Passivhaus/Code for Sustainable Homes. This can save building owners up to 70 per cent in energy costs.

Fire resistance: ICF structures offer maximum safety with a fire protection rating of up to four hours. With an ICF structure, walls are built with steel reinforced concrete and the forms are manufactured with a non-toxic fire retardant expanded polystyrene foam to ensure maximum safety.

Acoustic performance: ICF structures act as an effective sound barrier, filtering out unwanted noise, dampening sound vibrations from outside noise creating comfortable working or living spaces for occupants. ICF systems offer superior building comfort via excellent Sound Reduction Indexes when combined with a gypsum wall board finish and an exterior finish of acrylic/silicon render. Walls can be easily modified to achieve an SRI of SRI 72 (STC71) if the project requires.

Strength: ICF buildings provide greater impact resistance and will withstand winds of up to 250mph so building occupants are safe and secure in almost any situation. The strength of the ICF wall comes from the solid concrete core.