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ICF and brick and block

When you’re planning a self-build, there’s a lot to think about, not just in terms of planning and constructing, but in terms of things like insulation too. Here, we explore the relative pros and cons of ICF (insulated concrete forms) and brick and block to help you out.

What’s the difference?

Traditional houses are of course made with bricks and mortar. A brick outer layer is teamed with a block (usually aircrete) inner layer, with a cavity wall between being filled with insulation materials. ICF, on the other hand, is made of lightweight, hollow polystyrene blocks that are interlocked to create a house-shaped mould, called a formwork, which is then reinforced with steel and filled with concrete. Although popular across the world and particularly in the US, it isn't widely adopted in the UK; bricks and mortar have done a fantastic job here for centuries and the majority of self-build architects use them. There are different types of ICF – some use recycled timber mixed with cement or graphite, in addition to polystyrene. The type you choose will affect how your home is put together, so it's a good idea to select the type you're going to use before you finalise your design.

Comparing ICF and brick and block

As we mentioned above, ICF is an excellent insulator and highly airtight, which means your home should be energy efficient and economical to heat. It is usually a very good way of building to Passive House standard, as ICF homes tend to have few cold bridges – gaps in the insulation where heat can escape and condensation can form. It's also very strong and soundproof, lends itself to most designs, and can be externally clad in any material. Building with ICF is quick too, and can be done even in bad weather. If you’re keeping an eye on your self-build costs, however, brick and block may be more attractive as the materials are typically less expensive. There’s also the consideration of its popularity - because bricks and mortar are much more common here in the UK, finding a bricklayer is simple, whereas finding someone who can working with ICF is not. In addition, last-minute changes to the design are usually easier with brick and block - if the house needs to evolve in line with changing regulations or circumstances, this can be accommodated much more effectively.

Will using ICF make it difficult for me to get a mortgage?

It certainly shouldn't – ICF is recognised as a standard form of construction by the Council of Mortgage Lenders, as long as you use a firm accredited by the trade body, the ICF Association. It's also accepted by the major home warranty providers, including NHBC, the National House Building Council, which provides warranties for new homes. Our Architects in BexleyBromleyErithDartford and Croydon are here to help you with decisions like this, so whether you’re weighing up insulated concrete forms pros and cons for your self-build or getting ready to extend an existing property with bricks and mortar, we can offer professional advice. Contact us today about your project.
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