Self-build for beginners

BUILDING WITH INSULATED CONCRETE FORMWORK

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If you're planning a self-build, one of the biggest decisions you'll make is what structural system to use.

For most people, the options that spring to mind are either traditional brick and block or a modern timber frame. But another contender has been steadily growing in popularity - Insulated Concrete Formwork, also known as ICF.

ICF is often promoted as a fast, efficient and high-performance way of building. But what exactly is ICF? How does it compare to the more traditional building systems? And is it really a good fit for your project and plot? We'll explore all of this and more to help you work out if it is the best option for you.

WHAT IS ICF?

In simple terms, ICF is a building system where hollow blocks made from insulating material, such as expanded polystyrene (EPS) or wood fibre, are assembled on site to form the structural walls of a building. They're a bit like giant Lego blocks and lock together to form a continuous wall with a cavity which is reinforced and then filled with concrete. Once poured, the concrete creates a solid, monolithic structure sandwiched between layers of permanent insulation, which act as the concrete formwork.

The result is an airtight, highly insulated wall system that also has the robustness of reinforced concrete at its core. Unlike timber or masonry cavity walls, there's no cavity and no need for secondary insulation or additional vapour control layers or airtight membranes.

HOW DOES THE ICF BUILD PROCESS WORK?

The build sequence for ICF is quite different from laying bricks or erecting a timber frame, and is surprisingly straightforward. It starts with constructing the foundation or substructure, which supports the first course of ICF blocks. Accuracy at this stage is vital, because any mistakes will be magnified as the wall goes up.