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Prefabrication services
30 December 2019
Nitesh Panchal

DfMA – Why MEP Contractors Should Consider It

When something makes your life easier, why not use it? Design for Manufacture and Assembly (DfMA) is a building construction practice that involves integrating factory-built building components or modules on site. It is a practice that results in several advantages, but the most important ones are that DfMA facilitates improved quality, improved time management and a safer site.

As DfMA includes the assembly of prefabricated elements or modules, MEP (mechanical, electrical and plumbing) contractors can use prefabricated construction modelling, DfMA modelling and drawings and modular construction drawings to help deliver sound and accurate MEP services.

In addition to design, it is essential that the owners, design consultants and MEP contractors agree on the project’s timeline. Using MEP prefabricated modules in the DfMA process means that MEP designs must be finalised early on. That way, rework and other costly and unproductive delays can be avoided. The timeline comes into play even for procurement and logistics. Design decisions regarding factory manufacture must be finalised early in the planning stage, so that the requisite materials can be procured on time. To do so, the MEP contractors will collaborate with the general contractor and building engineering consultants. The input from the MEP contractors can be used effectively and thus help avoid additional costs and delays.

Project site supervision teams can monitor and supervise the work in progress at a controlled factory setting during the DfMA process rather than travel to the site. This becomes useful when MEP unit prototypes are being introduced. Instead of finding an area where the prototype can be tested on site before installation, using DfMA means that the prototype unit can be tested in the factory, inspected, tested and then mass produced in a location away from the site. Such a process helps to make sure that the MEP units are produced in compliance with drawings and specifications early on, avoiding costly rework.

To facilitate convenient methods of quality control, MEP contractors can use Building Information Modelling (BIM) services. The MEP BIM data can be accessed via a mobile to execute quality checks, inspect a site and supervise work progress. Checks that can be performed include the following:

  • Visual Checks
  • Interference Checks
  • Standards Checks
  • Element Validation

The MEP contractor’s team members can check on the quality processes and update the BIM model regularly in the DfMA process.

Notable Advantages of DfMA for MEP Contractors
  • Thorough Understanding – The DfMA process begins with completely comprehending the site and its features, the design brief, key constraints and important considerations.
  • Level of Detail (LOD) – According to project requirements, detailed data can be accessed, used and checked.
  • Safety – Experience and research shows that factory conditions are 80 percent safer than working on site.
  • Costs – Labour on site costs approximately double that required for factory-based labour.
  • Productivity – The rate of productivity in a factory can be as high as 80 percent, while typical site productivity rates hover around 40 percent.
  • Waste Reduction – Efficient factory settings can limit wastage of resources to just 2-3 percent and also recycle most materials.
  • Minimal On-site Labour – Since most of the MEP components are produced in the factory, on-site labour is minimised.
  • Manufacture of Kits, Modules – Kits with parts can be manufactured at the factory or workshop and easily assembled on site, and modules fitted out in a factory can be easily installed at the site.
  • Easy Site Reconstruction – With DfMA, components, modules and even entire buildings can be reconfigured and transferred to another site, thus re-using parts.
  • Minimal Site Delays – Typical on-site delays, such as lack of materials or labour, trade sequencing and rework, are all minimised and even eliminated through DfMA.

When looking at ‘fit-out kits’ delivered to the site, it can be observed that everything that is required for the relevant work can be created and delivered, such as :

  • Tested and terminated ‘plug and play’ wiring looms
  • Volumetric or flat pack bathrooms
  • Prefabricated services units, with boiler and water tanks, under-floor heating manifolds, electrical distribution boards, whole house ventilation units, etc.
Further reasons why MEP contractors should consider DfMA are as follows:
  • Expense– By using fewer parts, standard parts and hardware, removing unique parts and decreasing the labour count for assembly, and because the factory setting protects manufacture from weather conditions, several considerably high expenses can be saved.
  • Ease and Speed– Using vertical assembly and self-aligning components, it becomes easier and faster to assemble parts, disassemble them and repair them. There is a reduced need to reorient parts when they can be stacked vertically. Ball bearings, washers and roller bearings are easy to use in an assembly, since they are self-aligning. Fewer tools are needed to install self-contained MEP modules, saving time.
  • Testing– Modules can be optimised using BIM, and prototypes can be tested extensively, reducing risks.
  • High Efficiency– Consistent components that can be continuously modified result from DfMA, due to increased levels of quality control. Greater efficiency is achieved from fewer manufactured parts, resulting from reduced breakage and misalignment.
  • Less Site Visits, More On-site Space– When on-site space is limited and difficult to access, DfMA can lead to less material and labour on site, while helping maintain space on site for other activities.
  • Manufacturing Simplified– Using prefabricated modules helps simplify testing, inspection, assembly, purchasing, maintenance, redesign, service, etc. With multi-functional parts, several functions can be executed, such as projections, indentations, chamfers, moulded keyways, etc. Most of the steps concerned with cleaning and soldering can be avoided.
  • Troubleshooting– Prefabrication through DfMA simplifies assembly operations, inventory, maintenance, servicing processes and the identification of problems. With flexible interconnected parts and harnesses, connectors can avoid misalignment.

In the era of prefabricated construction BIM methodology, the DfMA process provides MEP contractors with a wide range of advantages, as can be seen above. It is crucial to employ accurate DfMA modelling and drawings in this process. As costs are continuously increasing globally, many Western firms find it advantageous to source their prefabricated construction modelling and modular construction drawings overseas, where they can enjoy the many benefits of precise DfMA modelling and drawings delivered by seasoned and well-qualified professionals, who are also cost-effective. For MEP contractors, these options are certainly worthy of consideration.