Design Considerations for Modular Builds

A detail-oriented design process, thoughtful creation, and review of submittals are vital to ensuring the project goes as planned.

Oct 30, 2023

Prefabricated sustainable timber office building
Prefabricated sustainable timber office building

The process of designing a modular building is complex. Depending on the type of structure, the Architect might have to design the building structure and the individual pods and then determine the best method to attach them. In other cases, an Architect might create an overall plan and then decide which sections should break into modular components.

Even more complex, some modular projects (many, in fact) have more than one Architect involved in the process—though one remains the design Architect.

This article highlights essential considerations that must be made by the Architects and Consultant team when designing modular buildings. A detail-oriented design process, thoughtful creation, and review of submittals are vital to ensuring the project goes as planned.

Why Modular?

As with most buildings, modular construction comes with its own challenges. However, there are a lot of benefits in terms of the time and money that can be saved. Manufacturing modular units off-site leads to streamlined production processes, which can reduce the overall schedule by 30 - 60%. Time is also saved by the reduced weather and logistical delays on standard construction projects. Modular construction is a budget-friendly option and helps eliminate waste and labour costs, which is especially important given the shortage of skilled labour we've been experiencing in recent years.

Overall, modular construction can be complicated and require a lot of planning. But you have to weigh the pros and cons to determine what is needed for your specific situation.

Modular Buildings: An Architect’s Role

While it certainly looks different than a conventional project, the role of an Architect in a modular or prefabricated project is equally, if not more important. They have different responsibilities, and small, individual decisions can impact the entire project.

Consultation with the Owner

First, understand that there are a few types of prefabricated projects: prefab, modular, and volumetric. 

  • Prefab is often used to describe all projects built off-site and installed on-site, but in reality, it pertains more to individual pieces such as framing members, glass features, and other Architectural touches constructed in an off-site facility. 

  • Modular describes structures designed to be built in sections of a building in a controlled environment and then delivered to a job site. 

  • Volumetric modular describes buildings with a superstructure and 6-sided pods built off-site and attached to the structure. 

It's an Architect's job to consult with the building owner to determine which construction method is best—conventional or some form of modular construction. The Architect then designs the individual components using modern software such as BIM (building information modelling) and other 3D models. 

At this point, the Architect helps the project owner choose a general contractor. This contractor is responsible for the site work and coordination but must be selected after the project type is determined and the plans are created. Typically, the contractor chosen has experience with prefab and modular construction and an in-depth understanding of these projects' site preparation and installation needs.

Note: In some cases, manufacturers may prefer to operate as their own general contractor on a modular project. When this is the case, the owner and the Architect must work together to determine if this is a good fit. These parties may already have a general contractor they trust and would prefer to use. 

Manufacturer Collaboration: Plans and Submittals

Once the Architect has the approval of the project owner on the initial design, they collaborate with the manufacturer. In some cases, the general contractor may also consult with the Architect and modular manufacturer, while in other cases, the modular manufacturer and general contractor might be one and the same. 

The manufacturer will review the plans once they receive them. Then, they'll start their design and material selection process and send a submittal package back to the Architect. These construction submittals contain all the specs, shop drawings, materials, and style choices that the manufacturer believes best meet the project's needs and the Architect's drawings. 

The submittal process is critical to modular construction. There must be a simple way to receive and review submittals and communicate about specifications and changes. With so much of the modular process hinging on repeatable designs, one small mistake could ripple through the entire project and cause a major disaster.

General Contractor Collaboration: Submittals of Their Own

As the general contractor begins the site work, they'll review the drawings, hire subcontractors, and source building materials. Eventually, they'll have submittal packages of their own.

Like the manufacturing submittals, Architects need to review these submittals and approve them or make corrections and recommendations. This aspect of the process is the foundation on which the rest of the modular project sits, so any foundations, steel superstructures, or infrastructure must meet the design requirements and building codes, and it's the Architect's job to ensure that they do.

Meeting Code

Since much of the construction process occurs in a controlled factory and units are delivered to the site mainly constructed, a traditional building inspection is not practical. A local authority must receive a stamped set of plans to approve the design for modular construction.

Once the designing Architect approves the submittal package, the manufacturer assembles the stamped drawings. They must be stamped by a state-licensed Architect, so the manufacturer may hire a third-party Architect or use an in-house Architect. In some cases, a second contract may exist between the manufacturer and the designing Architect solely for this aspect of the project. 

The manufacturing process can begin once the local authority approves this set of plans. 

Ongoing Inspections

One of the similarities between a conventional project and a modular project is that inspections are still necessary. However, rather than just visiting a project site, they'll also see the manufacturer's facility. Many Architecture firms find that visiting the factory weekly is vital to ensuring the project is on the right trajectory.

University of Toronto Modular Building Design by WZMH

The Deficiency Process

One of the risks associated with modular construction is the impact of a deficiency. While small punch list items are typical, repeated deficiencies can make or break a project.

Mistakes and deficiencies must be found early in the design and manufacturing process to prevent them from having an expensive, time-consuming impact on the project. Ideally, any potential issues should be discovered in the BIM process or in shop drawings and plans during the submittal process. As a third layer of protection, Architects should do their best to identify any issues during factory inspections. 

Submittals are Critical to Modular Construction

While conventional construction can be slower and less efficient, it allows for some flexibility. Modular construction only affords a little wiggle room. For this reason, the submittal process is an integral part of the modular construction process.

When construction submittal packages are easy to receive, review, and communicate over, Architects, design teams, and manufacturers can avoid expensive mistakes. Along with BIM tech, careful design, and factory inspections, submittals can help these team members catch deficiencies before the manufacturing process begins. This saves time and money and ensures the owner is satisfied with the finished project.

Additional resources:

Check out how WZMH is using modular design to rebuild damaged housing developments in Ukraine.

Habitat 67, designed by the Israeli-Canadian architect Moshe Safdie as the Canadian Pavilion for the World Exposition of 1967. This modular design has been replicated in countries all over the world and continues to this day to be an inspiration for modular architecture.

Crowne Plaza time lapse modular build video.

At Part3, we give you the tools you need to make your next modular build become a reality. Because Part3 is built by architects, for architects, we know what you need to get it done — on time and on budget.

Let us show you how. Set up a demo, or speak with one of our industry experts.