ICF - What is it? Why use it?
Shu have been building our experience for Insulated Concrete Formwork (ICF), and it has been utilised in one of our completed projects recently.
ICF is Insulated Concrete Formwork that stays in place as part of the building fabric. It is an in-situ modern method of construction, that speeds up the building process and helps to deliver high levels of performance making it suitable for Passivhaus and low energy buildings.
ICF is particularly beneficial because:
ICF adopts a fabric first approach: Prioritising the thermal performance of a building ensures occupants are comfortable and energy bills are minimised. The high thermal mass of the concrete also keeps the spaces cool in summer and reduces heat loss in winter.
The ICF is inherently airtight: This helped one recent project achieved an air test of 0.4m3/(hm2) to some apartments, whereas Building Regulations stipulates a significantly higher air permeability of 5m3/(hm2). As the concrete core forms the air barrier the integrity of this will be maintained over the life of the building, unlike a traditional barrier which is at risk of damage during the build and will eventually degrade over time.
Minimising the performance gap: Insulation creates the formwork for the concrete, and therefore must be continuous. This ensures the build quality is high with thermal bridges minimised and the u-values are reliably achieved.
It is simple to construct: The modular blocks of insulation fit together before the concrete is poured in and remain in situ. This simplicity speeds up the construction process and reduces the number of contractors required on site, which is particularly beneficial for a tight site
Light weight blocks: This allows the blocks to be easily moved by hand. This helps to create a safer working environment and reduces the need for expensive equipment.
External walls can be clad in a variety of materials: In our projects the finishes have included render, brick, timber cladding and metal cladding. The overall finish and appearance of the project is not limited by the ICF.
Material usage: ICF uses less materials than other construction types, and there are suppliers of concrete and EPS who use recycled materials. Additionally, these materials can also be recycled when the building reaches end of life. However, as with most materials there are pros and cons, it shouldn’t be ignored that concrete and EPS have comparatively high environmental impacts. That said, when comparing like for like, a typical wall achieving the same performance would involve similar quantities of insulation and materials. If you think ICF may suit your project, but are concerned about the carbon value, a whole life-cycle assessment can be undertaken.