What is Insulated Concrete Formwork (ICF) Construction?

In the world of construction, there’s an innovation gaining momentum: Insulated Concrete Formwork (ICF). Despite its modest profile here in the UK, ICF is beginning to stand out with its benefits in sustainability, energy efficiency and structural integrity. And it can even save you money! Imagine never having to put the heating on in your home? Join us as we shed light on this construction method.

Unlocking the Potential of Insulated Concrete Formwork

ICF represents a shift in traditional construction, replacing traditional bricks and blocks with modular hollow container blocks crafted from either polystyrene or woodcrete. These blocks serve a dual purpose as formwork and insulation. Steel bars are then used within the formwork blocks to create the structural integrity. The blocks are then filled with concrete and the formwork stays in place, providing the surface upon which the finishes can be fixed, both inside and out, meaning traditional methods like plasterboard and rendering can still be used.

The benefits of using ICF?

Making houses out of concrete may not be people’s first thought when creating a beautiful home but the benefits do speak for themselves.

• Save on Energy Bills: Insulation properties are incredibly good, home owners can save up to 70% on energy bills as it offers an incredibly low U-value (the measurement used in assessing how effective a building element is at preventing heat from transmitting from the inside to the outside of a building). The block itself is the insulation so you don’t need a cavity insulation that you would find in traditional construction.
• Noice Reduction: Its airtight due to greater insulation and thermal mass, so particularly good at keeping noise out. For example, if you lived near a motorway, it would keep the noise out.
• Quick Method of Construction: The formwork blocks are laid dry, meaning no mortar is used, as opposed to traditional masonry blocks which require a skilled trade with a brick layer on site. The forms are exceptionally light, so the manual handling on site is safer and allows for faster installation. Steel bars are used to reinforce the wall but these are easy to place because the blocks have pre-formed spaces to position the bars. Generally, there is nothing particularly challenging or difficult about this type of construction.
• Cost Saving: The build time is shorter meaning less spent on labour, hire costs and interest payments.
• Health Benefits: ICF boast mould resistant properties, contributing to better indoor air quality and lowering the likelihood of respiratory issues.
• Protects You from The Elements: ICF has superior fire resistance properties and is also flood and wind resistant.

Overcoming the Challenges of Insulated Concrete Formwork

While the benefits of ICF are undeniable, challenges and perceptions remain:

• Industry Awareness: Limited knowledge and experience with ICF pose hurdles to widespread adoption. We have experience of projects using both polystyrene and woodcrete systems.
• Supply Chain Integration: Integration of ICF into existing supply chains and construction practices is essential to realising its full potential and minimising costs. People tend to have preferred methods of construction based on previous experience, other times relationships with embedded suppliers and certain payment incentives can be barriers to considering alternatives.
• Design Complexity: Designing with ICF requires careful planning to accommodate its modular nature and minimise onsite adjustments. Setting out is critical and it means a clear vision of the building is required, emphasising the importance of early collaboration between the design team and the builder.
• Accessibility: The concrete must be pumped in to the formwork and not placed by hand, so this will require access for concrete delivery. Therefore, congested city sites or sites with narrow approach roads may prove a challenge.

Insulated Concrete Formwork Applications

Any design can be accommodated, be it curved, angular, cantilevered or built into the ground. ICF is suited to:

• Self builds
• Swimming pools
• Basements
• Retaining walls for gardens

It won’t rot, twist, move or shrink. These structures will stand the test of time. There is zero maintenance required for an ICF structure, and the only thing you need to maintain are the various internal and external finishes.

Insulated Concrete Formwork Engineers

If you are proposing to do an ICF self-build – how do you know if you need an ICF structural engineer? Working with ICF requires thought and it is best when we are brought in at the conceptual stage. Sometimes architects come to us when a lot of thought has already gone into the build, to then suggest “have you considered ICF?” is probably too late. It could mean too big a change to plan layout.

We are structural engineers for ICF, and the building overall. This means we can design and detail all the elements of the ICF and how it interfaces with the rest of the structure. We can produce drawings for the ICF walls and consider how everything fits together, from curves to cantilevers, as well as junctions and interfaces between steel beams, floor joists and rafters.

We carry out calculations for steel reinforcement in the walls, and produce bending schedules that specify the shape and number of bars, meaning a simple and accurate order of steel reinforcement can be placed.

If you are considering ICF for your build, don’t hesitate to get in touch, you can call us on 01794 524447 (Romsey) or 01225 251498 (Bath), or email us: [email protected]