As the industry works on how to hit the government’s housing targets, the ICFA discusses a relatively underutilised form of MMC – Insulated Concrete Formwork
Whether it’s building a scheme outright for affordable housing or meeting the requirements of Section 106, the challenges in affordable housing construction are real. For developers, there is the requirement to create affordable housing while remaining profitable and competitive in a market that has seen budget-busting inflation while also meeting tougher energy requirements.
To meet the growing tick list of requirements, developers need solutions that will deliver homes quickly and of high quality. It’s for this reason that Modern Methods of Construction (MMC) have increasingly become a talking point for the many notable benefits they bring to a site. Yet, the uptake in MMC hasn’t been as swift as hoped and with recent collapses of MMC manufacturers, there have been concerns over reliability alongside how they integrate into developments.
Yet, in the world of MMC, not all methods are built the same. Explore different options and you’ll find not all are offsite modular systems and there are some, like Insulated Concrete Formwork (ICF) which can easily slide into a developer’s build programme without long order timescales or hefty upfront costs.
What is ICF?
One of the biggest advantages of introducing ICF to a site is its similarities with traditional construction methods. ICF consists of blocks made from two layers of an insulating material with a hollow core. To construct the wall the blocks are stacked to create the wall, similar to traditional bricklaying, but instead of applying mortar to fix them in place, the ICF locks together via a raised profile. Walls are typically assembled in stages before concrete is poured into the block’s hollow core. Once the concrete has set, the installation continues until full building height is achieved. The blocks remain in place once the building has finished to provide two layers of insulation which wrap the interior and exterior of the building.
The strength of the concrete core means the same build method can be used for structural elements including supporting walls or overhangs. Indeed, without the need for complicated structural solutions, some conditions such as corner windows and cantilevered openings, are easier to achieve compared to traditional methods.
Affordable construction for affordable housing
One of the big concerns with contractors has been the cost of ICF. The initial outlay can be marginally higher compared to traditional methods although, with rising material shortages, the system is becoming increasingly competitive in price.
Once on site, ICF can significantly drive down costs. ICF offers a less capital-intensive option with shorter lead times and, due to the lightweight nature of the blocks, makes them much easier to transport with fewer deliveries. During construction, the building process, in only a few steps, incorporates the activities of up to four trades with the wall structure, insulation, air and vapour barrier already built in. ICF also enables follow-on trades to enter the building much quicker and continue the build programme.
The simplicity of an insulated solid wall construction method like ICF can also deliver a high-quality build that can reduce lengthy snagging lists. The concrete core already provides a strong structure but, with the blocks made from an insulating material, it provides the perfect environment for the concrete during the build. The ICF blocks enable the concrete to set quickly but cure slowly while at the same time protecting it from extreme weather which stops it from drying too quickly and reduces the chance of cracking.
Addressing the energy efficiency housing challenge
The built environment is currently in the spotlight to deliver changes by creating highly energy-efficient homes. Changes have already been introduced with the Building Regulations Part L interim measures improving carbon emission standards for newly built homes. Next year, tougher measures will be introduced with the release of the Future Homes Standard which is expected to announce that new homes will need future-proofing to meet even higher levels of energy efficiency.
Contractors need a simple build method that easily meets the standards. If built correctly, the monolithic concrete core of ICF creates an airtight, highly insulated structure typically achieving U-values around 0.18 W/m2.K or lower. The ICF wall also ensures levels of airtightness as low as 0.3m³/hr.m² and superior thermal bridging performance with Y-values of 0.02 regularly demonstrated using certified junction psi values. This results in even temperatures throughout the structure with reduced cold spots enabling the building to stay warm in the winter and cool throughout the summer.
Overcoming construction challenges
The construction industry is all too aware of the big challenges facing the industry. With a new Government, there are again new housebuilding targets to meet. Processes are set to relax by fast-tracking planning applications and freeing up development on grey belt and brownfield sites. Yet, there is still one big problem being ignored – the lack of skilled labour.
The CITB Construction Skills Network 2024-28 report announced concerning figures. To meet current housing targets their report estimates the industry needs more than 251,500 extra construction workers over the next five years. Not an easy figure when the industry loses almost as many workers each year as it recruits. None of it is made easier by the fact that almost a third of construction employees also find skilled staff a key challenge.
ICF could provide the solution. With the forms easily carried by hand and a reduction in heavy plant equipment on site, the technique provides a safer working environment. The simplicity of ICF also makes training on the system much easier and quicker than traditional build methods. It is possible to reach a competent standard much quicker and, without the need for mortar, providing the perfect training ground for apprentices while reducing the need for the number of skilled contractors on a build.
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