Insulated Concrete Formwork

Modern Methods of Construction (MMC) like Insulated Concrete Formwork can offer huge benefits for your project. It can help you to build sustainably, create an energy-efficient home and provide a higher quality of build.

Of course, one of the first questions most of us will ask is…how much will it cost? If it’s too expensive, then it’s not going to be the right system for you.

Of course upfront cost is one factor to consider but you also need to consider whether it will bring the project in on time, within your overall budget as well as delivering everything on your wish list. Awareness and popularity are growing in the different types of Modern Methods of Construction available to developers and self-builders. This offers lots of opportunities.

Insulated Concrete Formwork – Material Costs

A common misconception with Insulated Concrete Formwork is that costs for the materials are higher than traditional build methods. However, recent shortages and rising inflation have driven up the cost of materials. As a result, ICF has increasingly become a comparable solution. For example, in 2021 materials reached a 40-year high with data from the Department for Business, Energy and Industrial Strategy showing costs were 23.5% higher in August 2021 compared to the previous year. Timber saw one of the biggest increases at 52% while concrete only rose by 17% and ICF by 27%.

Aside from the upfront outlay, ICF can also cut costs in a number of other areas. Typically the system requires fewer deliveries in comparison to traditional materials and reduces the amount of mechanical equipment used during construction.

With ICF, the walls are built using large sized blocks made out of an insulating material (either EPS or Woodcrete). Concrete is then poured into a central cavity. As the formwork encases the concrete aesthetics of the material are not as important. This means you can use alternative options that contain more waste material in the mix, subject to structural engineer design. Finally, any delays on site add to the overall build cost. Lead times for ICF materials are incredibly short with stock by some of our ICFA members generally available for delivery to site within 48 hours.

ICF Build Costs

In terms of construction, ICF has numerous similarities to traditional techniques that contractors will already be familiar with. The forms stack and then lock into place through a raised edge profile which removes the need for mortar.

The simplicity of ICF speeds up the build programme so that you can reduce labour costs and it also doesn’t require the highly-paid skills of a bricklayer. This can typically result in the completion of a straightforward single-storey course in as little as three days, saving up to 60% on labour costs.

Keeping the Build Within Budget

This is where Insulated Concrete Formwork really comes into its own. Despite their shape and size, ICF can support almost limitless designs, using one system for the entire build.

• Blocks are available in different core widths and shapes which you can shape to any desired wall profile, including curved walls.
• Reinforcing bars are used to meet almost any engineering design criteria including above and below-grade walls, retaining structures and basements.
• The build system is supplied by one supplier removing the potential for overruns when dealing with multiple suppliers.
• It is incredibly adaptable. You have the possibility to make last-minute changes in the structure of the building right up to the point of pouring the concrete without incurring expensive redesign or manufacturing costs.
• The insulating property of the blocks enables the build to continue throughout winter. It is possible to assemble and cast in most weather conditions.

Save more with Insulated Concrete Formwork?

With ICF, the insulating material of the formwork encases the concrete. This has the benefit of letting the concrete set quickly but cure very slowly and continue to gain strength. Tests show a concrete block typically has a strength of seven newtons. Whereas an ICF building is around five times stronger at typically 35 newtons.

This offers multiple benefits to homeowners. The structure will need very little maintenance over its lifetime with only the external finish possibly requiring some work. It can also contribute to a longer lifespan for the structure. BBA certifications show that ICF structures will have a service life of not less than 60 years if the design is in accordance with the manufacturer’s specifications. However, it is widely understood that the lifespan of an Insulated Concrete Formwork property easily extends to more than a hundred years.

This same strength can offer huge benefits in extreme events such as extreme weather, fire and flooding. As a solid wall construction ICF, under BS 85500:2015 Flood Resilient Construction guidance is a recommended external wall method. If correctly designed and installed, the concrete structure has no voids and creates a watertight shell. In the event of flood damage, the insulating material in the walls remains water resistant, avoiding months of delays from drying out.

What does it cost to heat an ICF home?

The density of an Insulated Concrete Formwork structure offers superior thermal performance. The ICF blocks lock tightly together so they can hold the wet concrete in place as it dries. The monolithic concrete core sits in direct contact with the insulating block. This creates an airtight structure with exceptionally low U values, excellent thermal mass and a consequent reduction in energy required to heat and cool a property.

Monitored energy usage of a semi-detached 4-bedroom home with a basement with a useful floor area of 110m2 demonstrates heating and hot water costs are on average £250 per year which equates to less than £5 per week * (prior to 2022).