The myths of modular construction
Modular construction has changed radically over the past 60 years so it can be difficult to tell just what is fact or fiction. Kevin Jones, Director of Business Development at the Portakabin Group looks at the facts about modular construction in this myth-busting article.
 Myth 1 – Modular means temporary
It is correct to say that modular buildings can provide temporary solutions – but if the interim accommodation is supplied from a leading manufacturer, it will actually be constructed to permanent building standards.
Modular schemes generally have to meet the same Building Regulations requirements and standards as facilities constructed using site-based building methods. In fact, compliance can actually be easier with off-site construction.
The reality is that you are just changing the process – the building materials, such as the structural steel frame, remain the same as a site-based solution but construction takes place off site in a more controlled factory environment. This means better quality because the process is not subject to poor weather – which can cause serious quality issues post-completion, as well as a greater risk of delays and budget overruns.
 Myth 2 – Modular is all about ugly, grey boxes
Individual building modules do look like grey boxes but these units form the structure of the building and can easily be clad or combined with full-height glazing and a pitched roof for a completely different appearance.
There have been huge developments in modular construction and the approach can now deliver award-winning architecture and landmark buildings. There is a much wider range of aesthetic options that allow designers to achieve architectural variety for the building envelope, with all the speed and quality benefits of building off site.
Columns are no longer visible either internally or externally, for a seamless façade that can be specified with or without cladding. Options include a palette of attractive colours or claddings such as cedar, terracotta tiles, stone, composite metal panels, brick, and render.
Full-height curtain walling can reduce the reliance on artificial lighting and enhance the internal environment, and windows in ribbon, punched hole or composite configurations are factory-installed to improve safety on site and build quality. Roofing options range from standard flat, barrel vaulted, pitched or glazed atria.
A good modular building system will also create unrestricted internal spans of up to 12m using modules up to 18.75m in length for ease of space planning, and buildings up to six storeys high.
 Myth 3 – Modular construction is completely inflexible and restrictive in design and aesthetics
A technically-advanced modular solution can deliver more architectural and bespoke buildings with a much greater degree of design freedom. And the latest innovations offer even more options and flexibility:
- A much wider range of module length, height and width options for thousands of configurations, permutations and layouts.
- The option of using larger but fewer modules to reduce cranage, transport costs and site works.
- An wider choice of window and fenestration options, including full-height glazing.
- Sustainability features such as green roofs, ground and air source heat pumps, solar panels, solar shading and rainwater harvesting.
A traditionally-constructed building can even be extended with modular accommodation, and a wider range of module height options will facilitate the linking to existing buildings.
Modular buildings can be expanded both vertically and horizontally, without the need for decanting, and installation can be timed to take place at weekends or during holiday periods. The floor area can also be reduced or increased very quickly in line with local needs and capacity requirements.
 Myth 4 – Modular buildings have bouncy floors
A good manufacturer should offer a high performance pre-installed concrete floor which is ideal for high-traffic areas such as secondary schools and buildings that need to accommodate heavy loads or sensitive equipment, such as operating theatres.
A pre-installed concrete floor system integrated into the steel-framed modular manufacturing process allows concrete to be poured into individual modules in a controlled factory environment, for cleaner, safer and quieter work on site.
Performance specifications for high performance floors should include:
- A point loading of 7kN.
- A uniformly distributed load (UDL) of up to 9kN/m2.
- A concrete floor which is pre-installed to minimise work on site, reduce disruption and improve quality..
It is also important to note that specifiers are often not aware of the range of floor performance options that are now available with an advanced modular system. This should be able to deliver the different floor response factors required for a variety of applications and prevent over-specification. Hospital theatres and night wards, for example, require the highest specification, whereas offices have less stringent floor performance requirements.
 Myth 5 – Modular is a cheap solution
The reality is that whilst modular construction can be more cost effective, it is unlikely to be cheaper.
If you specify a system with the same high-quality components designed for longevity as a traditionally-built project, why would it be cheaper? You are simply moving construction into a factory, the materials remain the same – from the steel frame to the plasterboard.
However, there can be clear cost benefits when you take into account the advantages of the approach over site-based construction.
If you reduce the programme time by up to 50 per cent, you can occupy the building at an earlier stage for a faster return on investment. This can help LEAs address the severe shortage of school places – and healthcare providers reduce waiting lists more quickly.
There is also greater certainty of completion on time and on budget with a modular approach because construction in a factory environment is more predictable and less reliant on subcontracted trades. As a result, budget overruns and delays are less likely.
 Myth 6 – Modular means sub-standard accommodation
There should be absolutely no compromise on the quality of the accommodation because a building is manufactured off site in a factory.
As the demand for modular construction continues to increase, so has the number of specialist contractors. It is therefore critical to recognise that not all specialists are the same and the level of technical expertise and quality can vary hugely between suppliers. In the selection of a modular partner, construction clients should take care to compare solutions that are like for like.
Always visit completed buildings to assess the quality of construction and finish. Talk to other end users who have used the system and use their experience to differentiate the leading specialists from any poor performers.
Ask for statistics to show how much of the manufacturer’s business is from repeat customers. Ideally this figure should be more than 50 per cent – a good indicator of track record for delivery on time, and commitment to quality.
 Myth 7 – Modular buildings are cold in winter, overheat in summer
The quality of insulation for any building is key to ensuring it has a comfortable internal environment. All buildings should be designed to be warm and easy to heat in winter and to not overheat in summer.
The modular wall construction should offer good quality insulation in order to achieve the targeted U value. A production system that uses the latest open pour polyurethane insulation technology will deliver more consistent quality as well as zero ozone depletion potential, and reduced manufacturing time.
--Portakabin 13:50, 26 November 2014 (UTC)
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- Off-site prefabrication of buildings: A guide to connection choices.
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