Modular and prefabricated construction techniques are not a new concept, particularly for the UK construction industry. Post-World War II Britain saw a rise in the use of prefabrication in order to erect ‘temporary homes’ to combat a growing housing crisis. Since the 1950s, prefabricated housing has fallen out of fashion, with the Construction sector putting focus on both more traditional building techniques as well as modern construction advancements. However, the 21st Century has seen more modular building techniques at the forefront of UK Construction, with many commercial buildings constructed this way. In addition, modular construction is often utilised in motorway construction, to create bridges quickly to avoid congestion.
It’s not only the UK Construction Industry that utilises Prefabricated techniques. Sweden, Germany, and Japan are just a few front runners in Prefabricated Construction. In these countries it is much more commonplace to see prefabricated buildings, or even whole neighbourhoods. These countries are renowned for the quality and style of prefabricated constructions. The 21st century has seen more modular construction methods come to the fore.
Prefabricated construction, although most associated in the UK with Post World War Two housing, is going through something of a renaissance right now. Plant Planet’s Hannah Bounford explores the rising popularity of prefabricated construction.
What Is Prefabricated Construction?
The terms ‘Prefabricated’ and ‘Modular’ are often used interchangeably. However, the construction methods are not the same.
Prefabricated construction, often shortened to prefab, is an umbrella term for all methods of construction involving large components of the build being manufactured in a factory setting before transportation to the construction site.
Modular Construction, sometimes known as Volumetric Construction, is a type of Prefab Construction in which whole units of a building are constructed off site. Modular Construction is just one method utilising prefab components currently undertaken in the industry but is one of the most popular when adopting prefab methods – particularly in the construction of commercial buildings.
Despite the strong association with post WW2 emergency housing in the UK, prefabricated construction methods have a history dating to ancient times. The Romans, for example, used prefabricated sections of concrete to create aqueducts that would bring fresh water to their settlements. This early example of prefabrication in construction is reminiscent of the way in which motorway bridges are constructed of prefabricated concrete.
Today, like it has been since its conception, prefabrication is used most often when a specific section of the build is repeated multiple times throughout. For this reason, Prefabrication and, in particular, modular construction methods are most often utilised for tower block developments, apartment buildings or housing developments with repeated housing units.
The Prefabrication Renaissance
The ‘prefabrication renaissance’ has seemingly been happening for a few years now. Plenty of arguments have been put forward by those in the construction and architectural industries as to what the cause of the upsurge in prefab construction might be.
The predominant theory is that prefab construction techniques are increasing in popularity due to a need for more housing. Some sources estimate that the UK housing market needs to produce upwards of 300,000 new homes to support our population, which is growing at a rate of about 0.8% year on year. Prefab construction can aid the speed at which new homes are built, as on-site construction times are cut considerably. The use of prefab construction in new housing developments is particularly useful when many units are repeated.
There is another argument that prefab construction methods have become popular alongside the rise of programmes such as Grand Designs and George Clarke’s Amazing Spaces, which feature Scandinavian and European Prefab housing designs prominently. However, to counter to that, there is an argument that stands that prefab is not actually becoming more popular. By highlighting prefab construction methods on TV shows, public awareness of prefab techniques has grown, but this does not necessarily amount to an increased use of prefab in the mainstream UK construction industry.
In fact, home developers may have invested interest in releasing new builds at a steady pace. This is particularly viable in highly anticipated developments or developments in areas in need of housing. Releasing housing at a steady pace, rather than all at once, keeps house prices high meaning more profits for companies.
The UK Prefab Hybrid: a cost dilemma
Part of the reason that prefab housing may not be a common construction technique in the UK is the costs involved. Many companies creating prefab housing and developments are based overseas. Although some European and Scandinavian companies producing Prefab homes have branched out into the UK, there does not seem to be enough interest in the method for many of them to set up workshops. This results in high costs in the logistics of bringing prefabricated parts of the build to a site in the UK.
To avoid high logistics costs, UK companies have started to employ a ‘hybrid’ method of construction. This involves constructing larger components, such as timber or steel frames, off site before transporting them to be erected on site. Following this, cladding is added on the construction site to complete the build.
The story differs slightly for non-residential construction projects. Many industrial and business construction projects utilise Modular Construction. Modular Construction is attractive to companies looking to set up businesses in a short amount of time, as the method lends itself to shorter construction times overall. Elliot, the company who have had a longstanding contract with McDonalds to construct UK franchises of the fast-food chain can complete construction of one store within a five-week period.
Construction Plant in a Prefab Future
Two key questions remain:
- Will the way in which Construction Plant Machinery is used on site change if prefabricated construction takes off?
- Will the use of prefabrication methods alter the way in which plant machinery is developed?
The answer to both questions is ‘to an extent’. Some aspects of the building process reflect those taking place in traditional construction methods, however other aspects differ due to the nature of the construction techniques used. When utilising traditional methods of construction, the groundworks stage of a project can take months to complete. For projects utilising prefabrication methods, particularly modular building techniques, only a shallow excavation is required. During the groundworks phase, both construction methods, to an extent, require the same machinery.
For example, a key piece of plant used is excavators, but each method will use them to complete different requirements. A traditional build will require deeper excavation for building foundations, whereas prefab construction usually requires much shallower excavation. For this reason, lighter excavators may be used more commonly in prefab projects. Following excavation, both methods of construction may require concrete with flags or blocks on top. In both cases, plant such as cement mixers and concrete rollers may be required – particularly in larger builds.
Prefabricated construction, for the most part, takes place away from the construction site. Many components arrive at the site completed and ready to be lifted into place. For this reason, the use of cranes and high reach equipment is crucial for these projects. Cranes are especially crucial to larger modular buildings where the result is more than one storey high. The use of cranes to install prefabricated sections of a build alters other aspects of the construction site.
Most notably, in prefabricated construction there is a lack of formwork and falsework. The absence of temporary structures on site further reduces the amount of machinery required on site. While cranes are the most recognised piece of lifting equipment and used in larger modular builds, telehandlers are also used on smaller prefabricated construction sites. In addition, it is more commonplace to see mobile cranes on modular construction sites due to the faster turnaround of projects.
While prefabricated construction is not commonplace in the UK construction industry, the question of whether plant machinery development will be influenced cannot be answered easily. If prefabricated construction takes off in the UK market, it is conceivable that manufacturers would develop plant machinery specifically to aid the efficiency of prefabrication assembly on site. Perhaps the future holds autonomous prefabricated construction sites.