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Stages of the Modular Process

The modular building construction process and stages differ from traditional methods and include pre-construction, onsite and offsite.

April 15, 2019

Modular construction is an innovative and sustainable method of large-scale building, capable of delivering better results in less time, for less money. The modular building construction process differs significantly from traditional construction, which might leave some developers curious about what it actually entails.

This explainer breaks down the journey of a modular building, from idea to finished project.

1. Pre-Construction

As the name suggests, the pre-construction stage of the modular construction process encompasses everything taking place before the steel is cut and machinery hums. This includes design, engineering, and obtaining permits and approvals. iBUILT’s team of experts can assist you in every aspect of the pre-construction stage.


It is during the pre-construction phase that the design stage of the modular construction building process starts. It’s when the initial concept is formulated, and all design decisions and preparations are made. This includes central decisions, such as size and layout, right down to specific finishes, such as appliances and cabinetry.

At this stage, it’s important that the owner or developer has fully committed to building modularly. As deciding to do so later in the process will require expensive design changes.


Buildings are customarily designed using iBUILT’s state-of-the-art architectural and engineering technology with the utilization of BIM.

Obtaining Permits and Approvals

This modular stage also includes obtaining any necessary building permits.

2. Construction

The entire modular process is carefully crafted to eliminate inefficiencies at every step. The construction stage is where this becomes most evident, as there are actually two processes going on simultaneously. These modular construction processes are: onsite and offsite construction.

Onsite Construction

This is the phase that most closely mirrors traditional construction. Crews arrive at the future site of the structure and begin work on its foundation, sub-levels, and any support platforms for the modules that are due to arrive. In traditional building methods, this would usually require completion before above-ground construction can even begin, with the very real possibility of complications delaying the entire process. Not with modularization, though.

That’s because the fabrication of the modular units is already underway while the site is being prepared.

Offsite Construction

The modular units undergo several developmental steps within this process:

  1. Necessary materials are purchased if they are not already available. Structural steel is measured and plasma cut to the precise specifications of the design and prepped for assembly.
  2. Structural components of the module are built and assembled to form a six-sided unit.
  3. Framing begins, as floor, ceiling and wall joists are put into place.
  4. Sections of wall and flooring, assembled elsewhere within the facility, are fastened to the joists. Openings for doors and windows are cut.
  5. Technicians add all mechanical, electrical and plumbing (MEP) work from the outside of the module.
  6. The exterior of the unit is finished, and all openings for air filtration and plumbing are closed off until installation.
  7. The unit’s interior is completed. Finishes, from major appliances to aesthetic touches, are added.
  8. iBUILT fabricates modular units in its state-of-the-art Berwick, PA facility, which features two, quarter-mile-long assembly lines.

3. Building Installation

Once the modular units are complete, they’re delivered to the job-site and assembled into a building.

Final installation is fairly simple, and speedy, as most of the construction work has already been conducted inside the facility or onsite while the modules were being fabricated. The individual units are hoisted onto the foundation by crane and secured in place. They are assembled onsite. As units are added to the rising structure, teams connect, or “marry” them together permanently to ensure quality control.

The owner is delivered a stronger building in a fraction of the time ready to receive tenants or guests as soon as crews leave the site—with no delays, no overages, and no stress.


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