What expertise is needed to improve efficiency in Prefabricated Module Construction?

It’s not hard to understand why prefabrication and modular designs are increasingly popular. Traditional builds, where the majority of the work has to happen on-site, are open to greater safety hazards, potential delays due to weather and possible lack of co-ordination between contractors.

Technologies like BIM make it possible to design prefabricated modules, even for complex MEP systems, that can be built off-site to reduce timescales, rework and costs.

The role of the design team is vitally important in harnessing those efficiencies. To produce high quality prefabricated module drawings requires an expansion of the usual design role, where the design team must have solid expertise in

• co-ordination of services (particularly MEP)
• latest software tools & packages
• fabrication requirements
• transportation constraints
• installation & connection requirements

as well as all the usual design and CAD services needed for a traditional build.

How your designers set-up your project for success

We all know that potential efficiencies don’t necessarily translate into actual cost savings or reduced wastage on-site. Here are the key ways the right design team will ensure your project gains maximum benefit from the prefabricated, modular process.

Focus on co-ordination

Successful prefabrication requires a higher level of co-ordination than a traditional build to ensure the prefab elements can be installed without any issues. Service integration, space planning and scheduling usually need to happen much earlier to ensure the modules will work together as intended. All the relevant disciplines and sub-contractors need to be collaborating much earlier in the project than they would for a traditional build.

For example, maintaining construction tolerances at each stage of the project (design, fabrication, transportation and installation) is critical and requirements must be communicated to the different stakeholders at the right times.

Other use cases where co-ordination becomes critical are fire resistance and water penetration. Connection plates must be designed with due attention to fire-resistance at all joints, both interior and exterior. Exterior mate lines must also be designed to provide protection from water. In addition, without the correct detailing, the exterior connections can allow thermal bridging, which will affect the building’s energy efficiency.

Smart use of BIM

BIM (Building Information Modelling) is essential for complex projects where all disciplines and contractors need to work together seamlessly.

Because it combines geometrical modelling with layers of information relating to the materials, scheduling, costs (and more) BIM can be used to plan the sequencing in detail. Taking the example of construction tolerances, a high quality BIM will include materials and sequencing information that is easily accessible to all subcontractors. This ensures construction tolerances can be maintained and any risks are identified early on.

BIM is also a powerful tool for providing clash detection in the design of MEP systems, and clash detection is equally useful to avoid conflicts at the mate-lines between prefabricated elements.

At MultiCAD we use the latest Autodesk Revit software, which is compatible with standard BIM information architecture, for accurate project information that is easily shared among all stakeholders.

Design for prefabrication requirements and constraints

The design has to take into account the processes by which the modular elements will be

• individually assembled and built,
• transported from fabrication site to construction site,
• connected to each other and installed on site.

Each module must contain all the services required, meet the relevant building requirements (for example, fire protection) and fulfil the functions required for building users. In addition, designers need to consider the repeatability of modules, as the more times a single design can be repeated the more efficient the project will be overall.

In terms of transport, how the modules are transported to the construction site will introduce size, shape and weight constraints to the module design. Your design team need to be familiar working with these kinds of parameters and have all the relevant information about transportation methods and requirements. Consideration must also be given to the potential for damage or exposure to water during transportation and the design should mitigate the risks.

Prefabricated module drawings must also include how the modules will connect to the building foundations, elevators, stairs and other structural elements that have to be built on site. The aesthetics of the finished built are important too: will the mate lines between modules be concealed or used as part of the finished aesthetic? It may be different on the interior and exterior of the building.

Finally, the design needs to be smart about how modules connect to each other, especially if high repeatability of module design is part of the brief for the project.

Benefits of prefabricated module construction

The building itself can be prefabricated or individual elements like MEP systems can be prefabricated, depending on what’s needed for the project. In all cases, successful prefabrication depends on highly accurate prefabricated module drawings.

It offers the benefits of:

• More control over scheduling
• Quicker installation times
• Higher build quality & efficiency
• Safer environment for workers
• More predictable costs and cost savings

For prefabrication to work well, more design work must be done before technical approval than with a traditional build. Whereas the design and build phases traditionally overlapped, for prefabricated projects it’s advisable to complete design work before any fabrication begins. This avoids any costly changes to already fabricated elements, in the event that a design issue arising later requires rework of the modular design.

Ensuring compliance with building codes may also increase the scope of engineering work required in the early stages. This, along with more design work in the early stages, may lead to higher upfront costs.

The investment in the upfront costs makes it critical that your prefabricated module drawings are high quality, delivered by expert technicians. Careful attention must be given to efficiency of the fabrication process, size and weight of modules for transport purposes and their installation compatibility. Accuracy and high quality co-ordination at the design stage will ensure the improved efficiency, quicker installation times and project cost savings are realised in the later stages when the build comes together.

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