Profiting from the movement to volumetric modular construction

For decades, designs for the built environment have included modular units. Bathroom pods, kitchen systems, prefabricated panels, and other components designed by manufacturers have historically been specified as building components by architects. Such components now go far beyond modular elements to volumetric modular construction (VMC) units. Not simply predesigned elements of a project, volumetric modules are separate units that are stacked, plugged into a structural framework, or trucked to a site as a completed project, and architects design these modules.

Benefits of volumetric modular construction

Now more than ever time is money with the creation of capital assets. Although most construction in the US is, and has been, site-built construction, VMC is a paradigm shift away from traditional construction because units are constructed in a controlled factory environment. Under this approach, modules are built without delays caused by weather, labor disruptions, or other site problems because they are created off-site in a manufacturing plant, transported to the project site, then connected, stacked, or slid into a structure.

Modular construction is also beneficial because it is more precise construction with better quality control. Controlling the manufacturing process not only can result in less waste but also in increased performance and sustainability. In addition, as both construction laborers and experienced trade workers become increasingly scarce, off-site construction by a stable group of module constructors removes the issue of an insufficient or unpredictable supply of construction workers.

New family of documents from the AIA

Recognizing this trend toward prefabricating complete units, the AIA Contract Documents program crafted a new family of documents for both the architecture firm designing projects with volumetric modules and for the construction manager who oversees assembling the final project. In creating the family of VMC documents, the AIA Contract Documents committee looked at the variations in how states regulated the process, the role of design firms throughout the project delivery system, and risks assumed by the parties involved in the design, production, and assembly of the volumetric modules.

The family of documents include these listed below and the accompanying exhibits:

• A181-2025, Standard Form of Agreement Between Owner and Construction Manager as Constructor, Volumetric Modular Construction Edition
• A281-2025, General Conditions of the Contract for Construction, Volumetric Modular Construction Edition
• A481-2025, Standard Form of Agreement Between Construction Manager and Modular Subcontractor, Volumetric Modular Construction Edition
• B181-2025, Standard Form of Agreement Between Owner and Architect, Volumetric Modular Construction Edition

The documents committee also created a Guide to AIA Volumetric Modular Construction Documents, which is available as a free resource.

How projects are delivered using VMC

The architect provides design services in conjunction with subconsultants through the design development phase and then prepares construction documents. The construction manager (CM) provides pre-construction services and is responsible for the final modular design documents. The architect reviews the modular design documents for the limited purpose of checking for conformance with the architect’s design. (This diagram from the AIA shows the various contractual relationships on a project using VMC.)

As recognized in A481, VMC projects usually have one modular subcontractor to the CM. The subcontractor is a manufacturer that has a significant and substantial role throughout design and construction and is the party that designs and engineers the modules to meet the design specifications and to comply with codes and standards. The architect is responsible for the project’s design, including the incorporation of information provided by the CM and modular subcontractor into the project’s design, and the resolution of design conflicts between the project’s design and module design documents.

As with other project delivery systems, the architect visits the project site and, if designated as a supplemental service the modular facility or staging site, to become generally familiar with the progress and quality of the portion of the work completed. The site visits determine, in general, if the work observed is being performed in a manner indicating that the work will be in accordance with the contract documents when fully completed.

During the construction phase, the architect administers the contract between the client and construction manager but has no responsibility for the transportation, delivery, storage, protection, assembly, logistics, staging, or installation of the modules. This protects the architect from the perils intrinsic in the effort to construct, move, and install the modules.

The B181 addresses the specific professional liability exposures in VMC that can arise from various aspects of the design, manufacturing, and assembly processes, including:

• mistakes in the engineering design of the modular units that lead to structural failures, safety issues, or non-compliance with building codes;
• inadequate quality control during the manufacturing process resulting in defects in the modules;
• liability for errors in project management, including failure to properly supervise the assembly of modules, leading to defects or safety hazards; and
• failure of the modules to meet the specifications outlined in contracts or project documents.

Architects, of course, will still face disputes based on client expectations and miscommunication—misunderstandings regarding project scope, timelines, or deliverables can lead to client dissatisfaction and potential claims against architects for failing to meet expectations.

To mitigate these professional liability exposures, it is essential for architects participating in volumetric modular construction delivery systems to implement robust risk management practices, maintain clear communication with all parties involved, and perform their services in compliance with industry standards, regulations, and the reasonable contractual obligations in B181. Additionally, obtaining appropriate professional liability insurance can help protect against potential claims arising from these exposures. The Victor and CNA professional liability program offers broad coverage for architects and other design professionals providing services on projects using VMC.

For a more in-depth discussion of the new VMC documents, register for Victor’s upcoming webinar on the topic: Wed, Jul 16, 2025 1:00 PM – 2:00 PM EDT, titled: Volumetric modular construction: Understanding contractual and professional exposures in the delivery process, featuring Victor risk advisor, Frank Musica, and Robin Banks, a principal and attorney with the law firm of Goldberg & Banks.