Modular Construction: Repurposing Shipping Containers

by Marcy Marro | June 1, 2021 12:00 am

According to U.S. Customs and Border Control, approximately 24.7 million shipping containers arrive in the U.S. via seaports, trucks and rail. Many of these containers, once unloaded, are refilled with agricultural products or other export goods, and shipped back to foreign ports, but around 11 million worldwide are going unused. This surplus represents an opportunity and has hatched a growing industry, converting shipping containers into modular buildings.

Initially, containers were repurposed for storage spaces, semi-permanent commercial structures and single-family homes, but with a ready-made structure designed to be transported, lifted and stacked, developers and architects are increasingly taking advantage of this plentiful resource. We now see multistory apartments and hotels, as well as restaurants and other building types springing up from surplus containers. There are some regulatory issues and challenges to using shipping containers, but they also present some unique opportunities as the building blocks for modular construction.

As shipping container pioneers began seeking building permits for repurposed structures, jurisdictions recognized they needed to address this new construction type. States and other authorities having jurisdiction (AHJ) found that containers fell under their modular rules and regulations as they could be considered concealed construction. This means that many inspections and approvals fall under the scope of registered modular third-party inspection agencies for various states throughout the nation.

Another very important regulatory concern relates to the steel structure. Ordinarily, approval of structural steel includes steel mill reports and welding specifications. Approximately 97% of containers are built in China and these details are not available. In early 2016, International Code Council Evaluation Services (ICC-ES) introduced Acceptance Criteria 462–Structural Building Materials from Intermodal Shipping Containers (AC462) which established criteria and a protocol for evaluating the reuse of shipping containers as a building product. The criteria give AHJs and project teams clarity in how to ensure the structural integrity of repurposed containers.

If compliance with AC462 is not an option for a specific brand of container, there is another method of acceptance. Many projects will utilize a professional engineering firm that specializes in shipping container repurposing to assist them with the design analysis of the existing container and assist with the design of openings in the containers and site-specific elements.

These two paths are commonly accepted by most state agencies and local jurisdictions to demonstrate that structures will meet the intent of International Building Code (IBC) section 104.11 and the International Residential Code (IRC) as alternative materials and methods of construction that are not addressed in the code. Additionally, the International Code Council (ICC) has published the ICC G5-2013 Guideline for the Safe Use of ISO Intermodal Shipping Containers Repurposed as Buildings and Building Components that provides further guidance for code officials and designers.

There are other considerations and challenges to modular construction with containers. They lend themselves well to compartmentalized building types like apartments and hotels. However, there are structural limitations to the size and locations of openings that can be cut in the long sides of each unit, so open plan buildings are not a good fit for container construction.

Some of the materials in shipping containers need special attention as well. The lumber used for the floors are often treated to prevent environmental degradation and insect infestation, and may present health concerns for future occupants. To prevent indoor environmental quality issues, a third-party quality assurance agency needs to evaluate the materials and determine if any are toxic, and how to handle replacing, cleaning, or sealing of the wood platform as appropriate for the intended future use.

Increased demand for consumer goods during the pandemic temporarily changed some of the economics of international shipping, resulting in more empty containers being shipped back to Asia from U.S. ports. This has reduced the number of containers available for repurposing and increased the cost. This situation will likely be short lived, with the attractiveness of shipping containers as modular construction alternatives returning to pre-pandemic levels as trade stabilizes.

While creating some challenges, the pandemic has also spawned some new opportunities for shipping container repurposing, because they allow rapid construction and easy transport and set-up. A prime example is pop-up restaurants with drive-thru service or sheltered outdoor seating. These same advantages could help solve other unique development demands in the future.

We are currently supporting a client in the design and construction of an outdoor theatre with a stage, outdoor bar and ticket counter fabricated from shipping containers. The structures will help to define the outdoor seating area while providing secure cover for support spaces and equipment. The stage section will feature a hydraulic-lift door that extends and covers the stage area.

Despite some limitations, modular construction with shipping containers provides cost, schedule, and sustainability benefits that allow it to fill an important and growing niche. It has gained the support of the Modular Building Institute[1] and a growing fan base of developers, designers, and builders. With millions of shipping containers arriving in U.S. ports every year, and many of them not making the return trip, they are a readily available resource, ripe for creative exploitation.

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Alan Scott, FAIA, LEED Fellow, LEED AP BD+C, O+M, WELL AP, CEM, is an architect with over 30 years of experience in sustainable building design. He is a senior consultant with Intertek Building Science Solutions in Portland, Ore. Ryan Knowles has over 20 years of experience in the modular buildings industry and is an industrialized buildings manager with Intertek. To learn more, follow Scott on Twitter @alanscott_faia[2].

Source URL: https://www.metalarchitecture.com/articles/modular-construction-repurposing-shipping-containers/

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