Modern methods of construction (MMC) are increasingly being used in a wide range of construction projects
Despite this, misunderstandings about the risks MMC can present remain common
We weigh up the benefits and challenges of MMC
Although ‘modern methods of construction’ (MMC) is a 21st century term, it describes an approach to building properties more quickly, reliably and sustainably that has been developing over several decades.
While an increasing number of construction projects now involve the use of MMC, many organisations still have limited awareness of the associated risks.
Here, we discuss some of the most important questions to consider in relation to modern methods of construction.
1. What do we mean by MMC?
Most homes in the UK today were built using a traditional ‘brick-and-block’ approach to construction. However, alternative methods that depart from this approach are becoming increasingly common, particularly in the construction of social housing.
MMC is a collective term to describe these alternative construction practices. Off-site, factory production of the component parts of properties is a common characteristic of MMC. This includes ready-made walls, floors, roofs and entire rooms, which can be transported to their end destination for assembly, often in a matter of hours.
Timber-framing is another common example of MMC. Timber-framed buildings account for a large proportion of off-site construction, and more than a quarter of all new UK housing.
2. Why have modern methods of construction become so popular?
There are two main factors driving the growth of MMC, according to Stuart Blackie, Property Team Leader, Zurich.
“The green agenda is a major factor,” says Stuart. “Developers now have to consider sustainability targets, environmental impact, energy performance requirements and so on. MMC can make it easier to produce buildings that meet these demands.
“The other important factor is speed of construction. The UK’s housing shortage is well-documented, and one of the biggest advantages of MMC – and off-site, factory production in particular – is that homes can be built and delivered much more quickly.”
MMC offers a number of other advantages over more traditional construction methods.
Modular, factory-based production of component parts can result in more consistent quality of construction. Proponents of MMC say this can reduce the risk of defects
Off-site construction can also lead to more reliable timescales for construction projects, as factors such as adverse weather have less impact
The need for on-site labour is also considerably reduced
3. What are the risks of using MMC?
Despite these advantages, insurers have been concerned for some time that organisations do not always fully understand the risks involved when using MMC.
“Fire is a particular concern,” says Stuart. “Timber-framed properties are extremely vulnerable to fire, particularly during the construction phase, because the material is so combustible. We have experienced some fairly sizable losses due to fires during the construction of timber-framed properties.”
Buildings constructed using MMC can also present particular challenges for firefighters.
“Firefighters know how more traditionally constructed buildings will respond in the event of a fire,” says Stuart, “but with some of the materials and methods used in MMC, there may be less certainty.
“If firefighters are worried that a building could collapse at any minute, they are unlikely to concentrate their efforts on saving it. Clearly their focus will be on ensuring life safety and on getting everybody out, then preventing the fire spreading to neighbouring buildings. From an insurance perspective, this can result in far larger losses.”
Uncertainty over how materials will respond in a fire is a problem that can be exacerbated by a practice known as ‘product substitution’ (see boxout).
4. How repairable are buildings made using MMC?
Organisations also need to think carefully about how easy it would be to repair their buildings in the event of a loss.
“If you have a fire in an apartment block that has been built using modular construction, because of the way these buildings are assembled, you could potentially end up having to repair a number of apartments, rather than just the one directly affected by the fire,” says Stuart.
“You would also need to consider how easy it would be to obtain replacement modules if you needed to reinstate a building. If the company that supplied them was busy building 100 modules for another construction project, would they stop work on that project to help you reinstate just a couple of modules? Over time, product obsolescence may also present a significant risk in terms of future repairability.”
5. How should organisations weigh up the risks and rewards of using MMC?
Before embarking on any construction project involving MMC, it is important to ensure you understand what you are getting into, and that you are prepared to accept the level of risk that may be involved.
“It’s important to ask detailed questions during the design and construction phase to ensure you have a clear appreciation of the proposal and are going into it with your eyes wide open,” says Stuart. “It’s not a case of looking at MMC negatively; it’s about taking a balanced view, to ensure that associated challenges and risks are duly identified, considered and addressed, to ensure a successful outcome.”
For more information about some of the specific concerns surrounding MMC, read our previous News and Views article, Potential perils of modern methods of construction.