Why offsite construction is better?

Jamie Darragh, associate director at Black & White Engineering, talks about the advantages of adopting offsite construction, especially for MEP contractors


MEP contractors in the region should adopt offsite construction, according to Jamie Darragh, associate director at Black & White Engineering. He says: “Offsite construction has major benefits in the building construction sector and also for large MEP installations with long compact distribution/containment routes and plant room skids.”

He elaborates on some of the benefits for MEP contractors when it comes to adopting the offsite approach: reduced overall programme, which means reduced costs; reduced labour head count on sites; reduced health & safety concerns – majority of cutting, wielding and pressure testing is completed in the safe confines of the prefabrication workshop by experienced tradesmen with the correct tools and equipment at hand; reduced site management and documentation, e.g., hot works and pressure test permits will dramatically reduce; improved benchmarking and reduced coordination of interfaces – all interfaced connections for repetitive installations can be fully coordinated, built and benchmarked by the same prefab provider before it comes to site, with final ‘plug and play’ connections and commissioning completed at site; and finally, reduced material waste
However, Darragh says that “the industry must understand that offsite prefabrication is not a magic solution, which you sign off and subsequently witness the efficiencies and profits all fall into place”.
He says: “As with all new innovative site methods, there are some important prerequisites required to making offsite prefabrication a success. Early planning coordination and stakeholder buy in is key, which requires early design freeze of the multi-disciplined BIM model. This is essential with continuous input from the prefabrication team through the design period. Whether its plant skids, vertical/horizontal containments or complete technical rooms, each element of the proposed prefabrication elements need to be broken down to understand required interfaces (such as fixing details or BMS connections) and required programme date to meet final commissioning plan.”
Darragh says that by removing the process from an onsite operation into a controlled manufacturing process, the overall benefits to time and quality can be realised. He gives an example: “Take for instance a service module for a hospital, the systems that are normally installed through hospital corridors are extensive and require separate zones for individual systems. By integrating these systems into one major service module, there is the possibility to ensure full coordination and clear demarcation of service zones are considered.
“Another benefit is that the systems are individually inspected, commissioned and signed off prior to entering the site; the final connections and overall commissioning are made much simpler. This reduces the potential risk cost, by eliminating the chances of inconsistent approaches, due to multiple service suspensions from individual service providers.”
By utilising the offsite approach this also benefits the programme, progress and delivery of the project; in many instances, the whole solution can be completed offsite, delivered to site and connected in Meccano style fashion, says Darragh. For example, the equipment and piping of a prefabricated chiller plantroom can be fully installed connected, terminated, commissioned and signed off prior to delivery to site. Adopting this approach, allows the delivery of the plantroom to site to be incorporated onto the programme as a milestone event with certainty.
He says that the opportunities are endless, enabling the installation to be installed right the first time, thereby eliminating both unnecessary waste such as rework and time taken in obtaining signoff approval. “The MEP sector can only benefit from faster, safer and more efficient installations,” Darragh adds.


One of the major challenges in prefabrication methodology is to get “buy-in” for the project delivery methodology from the whole team at conceptual stage, early engagement and collaborative working is key. It is therefore, Darragh says, essential to begin with prefabrication in mind and ensure this becomes the driver for the project.
He says: “A prefabrication manager must be someone who understands the required process and when each designer/specialist input is required. Due to the way prefabrication integrates into a final solution, there is a need for the architectural team to understand and accommodate the prefabricated solutions into the building structure, by not understanding the prefabricated solutions, the allowances made for MEP services can be restrictive, and therefore compromise on the possibilities’ prefabrication can bring.
“Obtaining design freeze is also another driver to the delivery of the prefabricated solutions, without this it becomes a challenge to finalise the solutions.
“Arguably, the UAE industry could be better informed and equipped on prefabrication techniques and opportunities. There are a small number of MEP prefabrication workshops in the UAE, but they are not producing anywhere near the percentage of equivalent projects in Europe or the USA.”

Darragh does admit that prefabrication is a relatively untapped market within the region. He says: “The challenge here is to demonstrate the options, with the obvious benefits to the engineers, any decision to adopt prefabrication at concept stage must involve the engineers, to ensure they are fully aware of the options and obtain stakeholder ‘buy in’. But this is not just limited to the engineers, clients, stakeholders, designers, and architects, are just as important and in certain circumstances more so is the local authority engagement to ensure they are aware of the benefits of the offsite approach. As mentioned previously, early engagement, ‘buy-in’ and careful management is essential for this solution to work, this can only be achieved by making the industry aware of the benefits and willing to make it work.”
“It should also be considered that prefabrication as a concept is not limited to MEP, but can be adopted by all parties. Therefore, when designing the building, a clear understanding of the prefabrication options available for the building structure should also be explored, examples such as prefabricated toilet PODs, shower rooms, or on a bigger scale operating theatres/data centres are just some of the options available and which can benefit any project, no matter how big or small.”
According to Darragh, people tend to consider prefabrication as a more expensive option. He says: “Although there is a premium cost for the upfront planning and production of the offsite solution, benefits to programme, project overrun, labour rework, final signoff and delivery make this a more affordable option.” Offsite manufacturing is being implemented by all UAE contractors in some form, although it is still relatively in its infancy in the Middle East, says Darragh. Building construction activities are presently taking the lion share of the benefits but some MEP contractors are starting to push for further implementation of prefabrication.
He concludes: “At present, there is certainly a financial case to promote the benefits of prefabrication if managed correctly, something which is being achieved throughout Europe as a differentiator between the success and failure of a project.”

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