Inside the Modular Building Process
In this article, each step of the modular construction process will be explored and reasons for these advantages will be detailed.
The Advantages of Modular Construction
Modular construction (also referred to as off-site and/or volumetric construction) is growing in popularity because it offers several advantages over traditional construction. Chiefly, these advantages include:
- Shorter construction times (leading to a quicker ROI for owners), and
- Cost certainty (obtained through fewer mid-project changes and weather delays, and, to a lesser degree, fewer on-site injuries)
These advantages are obtained through a carefully planned design and construction process. Unlike many traditional construction projects, modular construction leverages a precise timetable and a predictable, industrialized assembly process to realize its value.
Step 1: Design approval by the regulating authorities and end users
In the modular building process, the project begins at the design phase. Architects and engineers, using building information modeling (BIM) systems and other software, create exterior and interior plans. Once plans are approved by the owner, they are submitted to the locality or third-party service for approval and building permit applications are submitted. The manufacturing of components begins once the design is finalized.
Note: Modular buildings must follow the local building codes and zoning regulations. The modular building contractor should already know the regulations that apply to the project based on the address of the physical building site and the agencies that have jurisdiction over that area.
Modular buildings must have approved and finalized designs before construction begins.
Step 2: Construction of modular components in a controlled atmosphere
The module components are built in a controlled offsite factory environment while site excavation and grading is going on at the same time. The amount of work (60% - 90%) performed in the factory can vary based on owner requirements. For example, it can include assembling basic structural components (like exterior and interior walls, flooring, and windows), installing mechanical, plumbing, and electrical components, and completing interior finishes such as drywall and cabinets. Because so much can be accomplished off-site, the labor force in the factory can consist of any or all of the following:
- Carpenters
- Drywall finishers
- Plumbers
- Electricians
- HVAC workers
- Painters
- Floor finishers, and more
A controlled factory environment allows modules to be built quickly, precisely, and more safely.
Inspections by a third party or other building code official takes place at various stages in the factory. Upon completion of the modules, they are prepared for transportation.
Step 3: Transportation of modules to a desired location
Modular buildings are shipped on chassis integrated into the structure or carriers towed by trucks. Due to the need to transport the modules to the final site, each module must be built to independently withstand travel and installation requirements (e.g., high winds, manipulation by cranes). Of note, the resiliency of the individual modules contributes to the greater structural strength of the final building, another advantage of modular construction.
Transportation of the modules depends upon some important factors such as the cost and method of transport, travel distance, and weight. It usually isn’t feasible to ship modules far due to road size and load restrictions. Generally, the maximum desirable distance for transportation of modules is 250 to 400 miles. The costs and transportation difficulties greatly increase for building sites farther than 400 miles.
The maximum width, height, and length of individual modules that can be transported is dependent on several criteria including local Department of Transportation restrictions; bridges, overpasses, utility lines that cross over roadways; and the actual route itself from the factory to the final destination. For ease of transportation, modules commonly have measurements of 15-feet wide, 12-feet high and 60-feet long, although these measurements can differ greatly in any direction based on a number of factors.
Transporting the finished modules to the jobsite can involve a single truck or many, depending on the size of the project.
Step 4: Erection of modules to form a finished building
Once at the jobsite, the modules are stacked by crane or rolled onto the foundation, bolted together and sealed for weather-proofing. The modules are then connected together, utilities are hooked-up, exterior siding and roofing components are completed, and site work is finished. The final construction stage includes completing exterior systems such as cladding, final caulking and sealing, adding stairs and elevators, and competing any interior elements such as painting, trim, cabinets, countertops, and installation of appliances that didn’t occur in the factory.
Modular construction offers an accelerated schedule for designers and builders and an accelerated ROI for owners. This is primarily accomplished by working on multiple fronts simultaneously. While modules are built and furnished in a controlled offsite location, site work can occur at the same time, eliminating the need for less efficient, strictly linear process.
This process—called parallel construction—is a key benefit of the modular construction process as it allows for reduced construction times of about 30% - 50% that of conventional construction.
Installing the modules happens quickly. In some cases, large multi-story buildings can be stacked in less than two weeks.
The process of modular construction is strict. Plans must be finalized early and stakeholders must have a complete understanding of the entire building process, but the advantages of modular construction are indisputable. To find a modular builder near you, click here.
More from Modular Advantage
Homes as Essential Infrastructure
The housing crisis is nothing new. Across the world, federal, state, and municipal governments of all sizes are struggling with how to provide more affordable housing—quickly—to those who need it. In Canada, Paul Halucha, Deputy Minister of Housing, Infrastructure, and Communities Canada (HICC), argues that the federal role in housing has shifted from funding at arm’s length to actively shaping outcomes.
Building the Future, Offsite
In the face of a national housing crisis, England stands at a critical inflection point where innovation, scale, and public-private partnerships must converge to meet an urgent need: more homes, and fast. Homes England is helping reshape the housing market by actively supporting MMC through a strategic blend of land development, financing, and grants.
How POJI and MOKO Are Industrializing Modular Construction Through Automated Engineering Systems
Working with Scandinavian Industrialized Building System (SIBS), POJI and MOKO helped realize a modular city concept located in Järfälla municipality of Stockholm, Sweden, with 350 apartments, communal areas, restaurants, small shops, and a preschool in a pleasant mix with experiential architecture and greenery.
Inside Boutique Modern’s Mission to Make First Homes Affordable and Efficient in The U.K.
The U.K.-based firm has been in business for 12 years, manufacturing houses for both private clients and local government, with a large chunk of its business coming from “affordable” and social housing. Working in a 32,000 square-foot factory in Newhaven, Sussex, Boutique Modern is changing decades-old thinking about constructing houses, all through the use of modular.
BoulderMOD: Producing Affordable Modular Homes While Training the Workforce of the Future
Colorado has been hit with a double whammy—a decline in the number of skilled construction workers and an increased need for affordable housing. BoulderMOD, a partnership among the city of Boulder, Flatirons Habitat for Humanity, and Boulder Valley School District, is tackling both problems and helping others do the same.
Guerdon: Seeking the ‘Holy Grail’ of Modular Construction
Guerdon, a modular manufacturer in Boise, Idaho, recently won what Laurence (Lad) Dawson, CEO and Managing Partner, describes as the ‘holy grail’ for a modular manufacturer. The RFP calls for a pipeline of six projects, totaling approximately 570
units.
State of Modular in 2025: Facing Reality
The critical and urgent reality is that the modular industry needs to open the doors to collaboration across all sectors. The sooner we stare down these challenges, the sooner we can welcome a new reality where modular is the dominant way to deliver housing for better performance, quality and all at a lower cost.
Modular Multifamily Housing as a Scalable Solution to the Housing Crisis
GreenStaxx provides a real-world, scalable solution through its standardized library of modular-ready multifamily designs and its innovative triple-decker model. Together, these offerings address the industry’s two greatest needs: efficiency and adaptability. By focusing on quality, repeatability, and collaboration, GreenStaxx is helping move modular construction from niche to mainstream and offering a practical path toward solving the housing shortage.
Sealed for Success: The Role of Waterproofing in Modular Construction
Water is one of the biggest threats to any building, causing structural damage, mold growth, and costly repairs if not properly managed. Waterproofing is the first line of defense, ensuring durability and long-term performance. As construction methods evolve, so do waterproofing solutions – moving beyond traditional coatings to advanced, factory-ready systems.
From Volume to Velocity: Scaling Multi-Family Projects Without Losing Control
When projects grow too fast without the right systems, factories run into problems. They miss deadlines, crews burn out, and quality drops. Instead of steady progress, chaos takes over. Things slow down, even with more units going through. That’s because building more isn’t enough—you also need to build smarter. That means shifting focus from volume to velocity.