Allison Whittington 12 March 2018

MMC: Knowing the risks

The UK’s housing infrastructure delivery has been under pressure for a number of years and the government needs a solution to achieve its targets at nearly double current rates.

Innovative solutions, such as using modern methods of construction (MMC) can provide a range of benefits, and are particularly attractive to the social housing sector and local authorities looking to construct public buildings in the most efficient manner.

We understand that new projects are increasingly looking to such methods to contribute to the volume of housing needed and meet the latest standards on sustainability and environmental performance.

Some popular MMC solutions can, however, introduce added risks, both during construction and throughout a building’s lifespan and there is a lack of understanding of the risks associated with properties built in this manner.

Timber-framed buildings

The insurance risks around MMC building techniques often relate to timber frames after fires have occurred both during and after construction. This building technique now accounts for around 25% of new homes built in the UK, according to the Structural Timber Association. Consequently, the STA has introduced a number of fire safety initiatives in order to improve performance of such builds.

Therefore, fire protection measures must be a priority in design and construction phases for all timber-framed structures. High quality of construction and contractor awareness are essential to ensure measures such as correctly specified and installed fire stopping are provided.

Modular construction

Off-site construction is a growing trend in the UK and now accounts for around 12% of all projects. One method, that of volumetric or modular construction, allows for factory-produced units to be placed straight on to prepared foundations, which in many cases reduces overall construction contract periods. However, the ability of some MMC materials to withstand the effects of flooding or water damage may be unproven.

In addition, some problems with such constructions may only become apparent years after completion, for example if the lower sections of the units were damaged or incorrectly specified during assembly and the structure is subsequently subject to flooding.

Pre-fabricated units may not be able to be repaired in situ and, dependant on the design of the specific system, may need to be removed and replaced. Such measures would clearly cause disruption to and removal of the surrounding pods or units and external finishes increasing reinstatement costs in comparison to more traditional build.

Similarly, where component parts are fixed together – notably modules and pods – there may well be hidden voids through which smoke, hot gases and water can permeate throughout a building, leading to even a small incident causing a disproportionately high loss.

Dangers of new technology

Some MMC, by their very nature, are new and innovative. For this reason alone, contractors may have little or no previous experience of the materials, systems and assembly techniques required. This again could lead to additional risks, particularly in relation to fires if contractors are unaware of hidden combustible insulation, than if more traditional methods had been used. There could also be problems in obtaining replacement components in the future.

Excellent contractor and management selection is, therefore, essential in order to ensure a full understanding of the MMC techniques being utilised, their likely performance including life cycle requirements, and how resilient they are to changes and adaptions throughout the life of the building.

Question marks, too, have been raised over the fire performance of some of the insulation products and materials used both within building structures, and on the external faces of buildings of both new and existing buildings, whereby their combustibility can significantly increase fire risks.

The overall fire performance must be carefully considered when using MMC – including weighing up the combined properties of materials – with a need for ‘joined-up’ thinking throughout the design, build and maintenance process to ensure that the true risks are recognised and fully understood by all stakeholders.

Risks associated with MMC are not easy to assess, however. That is why at Zurich we stay abreast of new technologies and witness fire and flood performance tests on materials.

Allison Whittington is head of housing at Zurich Municipal

This feature first appeared in Public Property magazine. Email to sign up to your own free copy.

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