The principles of off-site construction have been widely used in buildings in other parts of Europe; however it has taken time for the concept to be adopted in the UK. The idea is that many components of a building can be manufactured and assembled in a factory and brought to site in a part made form.
Benefits of Off-Site Construction
There are a number of key benefits to pre-assembled construction. Firstly the site preparation and manufacture of building parts can occur in unison – one doesn’t have to wait for the other. This can speed up the construction process and reduce completion times by up to 50%.
When the pieces do arrive on site, the build can progress quickly and efficiently. All parts can arrive in one delivery, ready for the final assembly. This reduces the number of journeys being made to and from the site, lowers the costs of machinery hire and can reduce the labour costs by around 25%. This makes for a productive and cost efficient construction method.
The reduced traffic on the site has many advantages. Firstly in terms of disruption to the client and local community, which is particularly evident in urban areas where the impact can be widely felt. A clear example would be the construction of additional buildings on a school or hospital site.
Laing O’Rourke has been pioneers in adopting off-site construction practices in the UK. Their investment in this style of building has helped to make improvements in the scope, quality, design and materials used in pre-assembly. They recently used this approach to create a £160million Cancer Centre at Guys Hospital in London. The building was erected quickly and efficiently to minimise the disruption and noise for hospital patients and staff.
Off-site construction can include plumbing, lighting, plastering and other trades. Working within a factory environment, they aren’t held up by waiting for the windows to be installed or other on-site restrictions. This can also reduce the need for them all to be working around each other in a limited space. Such factors not only make for favourable working conditions and efficiency, they also reduce health and safety risks.
Disadvantages of Off-Site Construction
In the early days of off-site construction in the UK, building designs could be restricted by the available materials and assembly techniques. Things have progressed considerably over the past decade and this is no longer an issue, although some companies were put off in these early stages of development.
Accurate measurements and careful planning are crucial to the success of pre-assembly. Every detail needs to be carefully planned before work commences, to ensure that it all fits together easily when the parts reach the site. A miscalculation or lack of co-ordination can cause considerable problems and delays, which immediately invalidate many of the benefits of this method.
Further Points to Consider
Effective planning and co-ordination are being widely encouraged within the construction industry, with a growing commitment to Building Information Modelling (BIM). BIM is increasingly the foundation for new business practices and company standards, so everyone in the industry is being encouraged to understand the benefits of this collaborative approach and how the available BIM technology supports the changes. Whilst BIM presents a considerable investment of both money and time, implementation will result in a far greater number of opportunities and contracts in the future, so avoiding BIM could be detrimental to the future of a construction company.
Whilst off-site construction can help to improve site safety, building sites remain one of the most hazardous working environments. Awareness of health and safety issues and the implementation of best practice remain a priority. All site managers should still be encouraged to attend SMSTS training courses.
Whilst traditional construction techniques still dominate, it is likely that the industry will see a growth in pre-assembly over the next decade.