Myths of Modern Methods of Construction

Stephen Wightman
Most of the myths of MMC and offsite construction can be busted under scrutiny, and when MMC is the right choice, it can deliver real value for clients and all parties in the construction process.

However, it is not a one size fits all solution and needs to be properly analysed and considered at the earliest possible stage in the construction process, with well-informed and knowledgeable professional advisors, to ensure that it is used appropriately and where it can deliver the maximum benefits.

I’ve answered some of the most frequently asked questions and misconceptions about MMC that I hear from project teams.

Isn't MMC the same as Modular Building?

No - MMC covers a range of solutions from simple components right through to full modules and should be thought of as a process rather than a product. The clue is in the name Modern 'Method' of construction. It is not a one size fits all solution but a range of solutions and elements that can be used right through the construction process to add value and benefits. Modular buildings are just one type of MMC building.

I can't have a choice with MMC...

MMC techniques use exactly the same materials and processes as traditional building so whatever choice is available in traditional construction will be available in an MMC solution.

Will MMC restrict my choices in design?

If MMC is not the right choice for the project, then it may well restrict what is seen as choice. But that is like saying using bricks restricts my choice - of course it does but not if bricks are the right solution. Good MMC design works with the design team to add the benefits with little or no negative impact. The important thing is to fully review the requirements of a project or programme of works at the very earliest stage to fully understand what are the drivers behind the project and whether adopting some of the categories or processes of MMC will add value to the programme or project.

MMC  is not durable...

MMC produced buildings are as durable as the materials specified to make them. The original prefabricated housing was only designed to last a limited period of time. Temporary classrooms are exactly that - temporary. Modern MMC projects are built with the same materials and design standards as any traditional building and will last at least as long as the minimum design life.

MMC performance levels are not good enough...

The performance level of a building has nothing to do with the way it is constructed but everything to do with the materials it is made from and the standards and design criteria to which it was produced. In fact, in some ways, MMC buildings outperform traditional buildings. Buildings delivered by Category 1 (volumetric or modular) and Category 2 (large format panelized) systems have been achieving levels of airtightness 3 times better than the current building regulations standards for years.

Standard sizes are the most efficient, so my building won't work for MMC.

For some formats of building high levels of repetition do offer some advantages this is not always the primary driver behind the adoption of an MMC strategy for building delivery. The level of disruption permissible on a project is the most important aspect of a project delivery e.g. in a working hospital environment or the certainty of having the building available on a particular date e.g. at the beginning of a school term. In these cases, the benefits of MMC mean that the building format is less important and as there are very flexible MMC solutions in the spectrum of delivery options there will most often be a format that works.

The contractor wants to be paid in advance, unlike a traditional project.

It needs to be remembered that in a project with a high level of offsite works that there are effectively two construction sites - the factory and the final site. The level of works being carried out in the factory would normally have been carried out and site has been applied for and paid for on a traditional project so the level of payment for works committed is no different, it is just in a different place.

The cashflow is too steep.

Cashflow in an MMC or offsite project appears steeper because it is normally compared to the start date but this needs to take into account the fact that the building is being delivered earlier than it would have been under a traditional scheme. When you actually compare the total “cash to keys” time this is shorter and therefore has a positive benefit to cash of using an MMC solution.

The design process is too fast and decisions are required too early

It is true that in an MMC project the Design processes are more stacked as some of offsite manufacturing is taking place at the same time as the infrastructure and on site processes such as foundations or groundworks. However, as with the cash flow issue, the building is being delivered and handed over faster so when you compare design works and decision dates with the finishing date they actually are earlier just more compressed.

MMC is more expensive!

On the face of it using an MMC technology or process can appear more expensive but not when the value of the benefits is properly considered. If the project team is looking to accelerate a traditional construction project, then acceleration costs would be considered as a way of achieving this aim. Why then is the faster programme benefit of a volumetric delivery method not considered in the same way? A well-considered MMC process that is the “best fit” for a specific project should be cost neutral when accurately compared with its traditional counterpart and value appropriated into benefits.

I tried MMC and it didn't work

Projects have challenges and fail regularly but in reality, is usually nothing to do with the process that was used to deliver but about whether the right process was chosen to fit the project or programme requirements. If a traditionally built project fails no one assumes that therefore traditional building doesn't work, the problem is usually identified as the wrong contractors, design, procurement strategy or some other factor. A well-conceived MMC project with the right design, procurement strategy and contractor will be successful as any traditional project and deliver the additional benefits of MMC.

MMC will save money…

This all depends upon how you view costs and they are allocated within a project. At the raw materials and labour level, it is very unlikely that the Contract Sum Analysis (CSA) will show a saving. This is because although labour productivity will be higher (easier working conditions, less cost time) the material content will normally be slightly higher due to duplication of some structural elements in order to provide sufficient strength and segmentation of the elements. If the benefits of an MMC solution are attributed a real value in call in the cost plan, or one of the benefit factors has a financial impact (for example costs for accelerating a traditional build which could be a provide which could be provided by a volumetric solution), then when fully analysed this could show a saving for using an MMC system. Over the coming years, as increased performance levels are required and with the moves to net zero, some of the intrinsic and in built benefits that MMC techniques provided will start to add costs to traditional schemes and may well then generate savings for MMC.

The only advantage of MMC is faster programmes

Whilst this is a widely acknowledged and easily measurable benefit of MMC (with up to a 50% of saving in a programme time in some cases) there are a much wider range of benefits associated with the use of MMC in delivering construction projects. The additional advantages are principally; quality control (much easier in a dry clean factory environment); Improved Worker Health and Safety (work is better planned, less variable, less work at height, not subject to suit weather and conditions); reduced site disruption due to fewer deliveries, trades and time on site; greater predictability by removing the influence of site conditions, variables and the weather; and more sustainable as MMC design delivers better thermal performance, less waste and reduced embodied carbon.

I won't get the same guarantees with an MMC building

It needs to be remembered that MMC is a process not a product and that any warranties and guarantees available in the traditionally constructed building, for example NHBC warranty, are available in a building constructed using MMC techniques. In fact, due to the better control of the processes and the fact that the construction is not affected by the weather level of assurance of quality and durability of build is actually higher with an MMC building.

I won't be able to get a mortgage or insurance on an MMC house

As houses (and any other buildings for that matter) constructed using MMC techniques are built from the same materials and techniques as traditional buildings, just with the better quality control and more robust detailing, there are no problems in getting mortgages or insurance on a building delivered using MMC techniques.

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