A guide to prefabrication (and how it’s transforming construction)

Posted on: 25 March, 2024

While prefabrication is emerging as a sustainable innovation in the construction industry, it’s actually a concept that’s been around for thousands of years.

Construction is a complex and multi-faceted process. From conceiving a project and procuring materials to preparing a job site and constructing the building itself, there’s a lot of organisation – and energy-consumption – that goes into bringing a project to life.

With three-quarters of the existing infrastructure that will exist in 2025 yet to be built, the need for infrastructure is increasing in line with a growing population. Yet with growing concerns surrounding the built environment’s contribution to manmade emissions, firms and corporations in the sector are looking at ways to make building lifecycle a more sustainable process.

There have been many innovations and advancements towards a sustainable built environment in recent years, such as retrofitting, lean construction and adaptive reuse, but one practice that’s quickly gaining popularity has already been around for thousands of years – prefabrication.

What is prefabricated construction?

Prefabrication is, as the name suggests, a process where parts of buildings are fabricated or ‘pre-built’ in a different location from the building site. They’re then transported to the final site where they’re set up.

In traditional construction methods, the materials of a building are transported to the site and constructed into parts of the project itself there. In the prefabrication process, only the foundations of the building are constructed, while other sections are preassembled and then transported to the site.

As an example, civil engineering projects, such as bridges and dams, have their steel frameworks of up to 37m preconstructed and delivered to the building site.

Prefabrication vs offsite and modular construction

Prefabrication isn’t exactly the same as offsite construction, although they’re often confused with one another. Offsite construction is broader than prefabrication – it refers to the overall process of construction, from planning and design to fabrication, being performed offsite and then delivered as a complete project to the final site. Prefabricated construction techniques focus on specific elements of this – the manufacture and assembly of parts.

It’s also slightly different to modular construction, which is another growing trend in the built environment. While prefabricated buildings can involve an array of components, modular buildings focus on the creation of modular units or ‘modules’ – repeated sections and standardised designs.

Modular structures have been adopted in the UK to help expand NHS infrastructure, as the repeated designs are cheaper than traditional building components and offer more flexibility.

Learn more: Modular construction 101: here’s how it’s making buildings sustainable

How long has prefabrication been around – and why are people talking about it now?

What’s interesting about the emergence of prefabrication in recent discourse is that this method of construction is not a new concept. The world’s oldest known railway, the Sweet Track, was built in England almost 6000 years ago and consisted of prefabricated components that were built off-site. There are various other examples of prefabrication throughout history, all the way up to the Second World War.

Today, prefabrication is a global trend, and often identified as one of the new modern methods of construction (MMC). In Sweden, 84% of detached homes are built with prefabricated timber elements. In the UK, imports of prefabricated buildings or modular units have doubled since 2019.

Here are the biggest benefits of prefabrication that are driving this growth.

6 benefits of prefabrication

1. Faster build time and cost-efficiency

Prefabrication can be faster than traditional construction methods, as the components are already built when they arrive – all that’s required is to put them together. Constructing modular buildings is faster still, with these construction projects completed 50% faster than their traditional equivalents.

There are also cost savings to be found in prefabricated structures, as transporting components and partial assemblies from a controlled factory environment can be cheaper than moving pre-production materials and resources.

2. Reduced pollution and improved sustainability

While, on the face of it, it may seem less environmentally friendly to have to transport prefabricated materials to a site separately, constructing pieces offsite actually present a number of benefits for the environment.

To begin with, constructing materials for buildings at different locations can reduce the size of the construction site, and subsequently the damage to the surrounding environment. It can also decrease the amount of noise pollution and traffic disruption, which, on a conventional site, can lead to greater fuel consumption.

Traditional building sites also produce a significant amount of waste – an environmental impact which is exasperated when waste from different structures and components is mixed, making it harder to separate. The end result is a lot of this waste ends up in the landfill – something prefabrication can circumvent, leading to a lower carbon footprint for a building project.

Learn more: Making a business case for sustainability: why now is the time to act

3. Greater quality control and durability

Constructing materials at factories rather than in the building site can provide an added layer of quality assurance. These indoor factories are protected from weather, which can often damage materials and delay and impact the building process. When it comes to quality control, it’s also easier for individual items to be checked in factories before they’re dispatched to the building site and ahead of the construction process.

What’s more, prefabricated materials are often much stronger than those used in traditional construction and are built to endure long-distance travelling.

4. Less health and safety risks

Along with protecting materials from bad weather and reducing delays, prefabricating materials by specialists in controlled environments can help reduce health and safety risks, as components can be built in concentrated environments and away from the busyness of the traditional construction site.

5. Address labour shortages

The construction industry has long been plagued by a shortage of labour, with many deeming it an even bigger issue than rising material costs. This lack of personnel is driving an 8.3% increase in construction costs over 2023.

Prefabricating materials and components off site allows building sites to be smaller and reduces staff requirements – meaning you’ll need less construction site managers and less labour productivity, meaning you can save on the costs of personnel.

6. Improved site security

Theft from UK building sites costs the industry £800 million a year. When you consider the size of these sites and the amount of materials located there – particularly in traditional projects where components are assembled in one place – it’s not a surprise that they attract thieves, or that construction companies have a hard time keeping them secure.

With faster turnaround times and smaller building sites, prefabrication can reduce help you keep the site secure and leave it less vulnerable to theft and vandalism.

The disadvantages of prefabrication

While prefabrication can offer a raft of benefits, it may not be optimal for every project. There are several potential drawbacks of prefabricated construction methods, including:

• Transportation challenges: Transporting your prefabricated components presents several logistical obstacles. Depending on the size of the components, traffic, height restrictions and maximum road widths can all make getting your materials to the site safely is a challenge that could outweigh the benefits of having them prefabricated – especially when these difficulties can drive up the cost of transporting them.
• The need for close cooperation with partners: If your components are being prefabricated off site by another party, there needs to be close communication and cooperation to avoid mistakes and errors in mass production.

Like many of the sustainable innovations and alternatives emerging in the construction industry, prefabrication isn’t a fix-all solution. However, if you’re able to make it work for your building projects and integrate it alongside other new measures, it can offer significant benefits while helping address the environmental impact of your construction projects.

Sustainability isn’t a passing trend – it’s here to stay and is constantly evolving. If you want to inspire and action change in your career, UCEM’s MSc Innovation in Sustainable Built Environments will give you the skills you need, both now and in the future.

Find out more: MSc Innovation in Sustainable Built Environments – University College of Estate Management