Modular construction and prefabrication of design has been growing in popularity in the design and construction industry over the past decade. This is the process by which building components are standardized and prefabricated, either on- or off-site, in a controlled environment and delivered to the construction site for assembly. This process provides the opportunity to realize efficiencies in the design and construction processes through standardizing building elements and repetition of on-site assembly.

The concept of modular construction dates back to the 1600’s, when the first reported modular homes were brought to colonial America by a fisherman who wanted a home built with English construction methods. This continued in the 1800’s during America’s rapid expansion westward, when mining towns boomed through the California Gold Rush period, and housing was in dire need. As a response, homes were preassembled in factories in New York and shipped across the country.

Again, after World War II, modular construction increased in popularity when the need for housing soared. Sears, Roebuck and Company had a full catalog of prefabricated homes to purchase for assembly on your property. Even Frank Lloyd Wright joined the effort with the Usonian Homes concept, the goal of which was to design simple, modern, affordable custom homes.

 

 

With modern technology such as Building Information Modeling (BIM) and other advancements, the modular construction approach has become increasingly popular for a range of larger projects, including educational facilities. The shortage of skilled labor available for on-site work and increased demand for projects with limited budgets and schedule are the main driving factors for standardization in construction. This, combined with improved technology, lower tolerance for safety and risk, as well as the need to deliver high quality facilities, has contributed to its implementation in today’s construction industry.

Modular construction can be categorized as volumetric and non-volumetric. Volumetric elements are individual three-dimensional units with enclosed space which are intended to be connected on-site to form a single building. This is the standard pre-checked modular classrooms that have become customary in today’s construction world.

 

 

 

The non-volumetric approach is a type of modular construction where building components, referred to as sub-assemblies, are fabricated and then connected on-site. Examples of this would be structural steel frames, beams and columns. It also includes sections of building facades, wall panels and interior partitions.

It is important as an architect to set a standard module early in the design. This allows for better efficiency in construction, less construction waste and ultimately provides a cost effective building. The more standardization of design elements that can be achieved, while meeting the programmatic goals and required building functionality, the more efficient the process becomes.

The quality of sub-assemblies can increase as they are fabricated in a controlled environment. These standardized elements have a high level of quality control, ensuring components are installed quickly and meet tight tolerances. There is also time saved in standardizing sub-assemblies because each component does not have to be custom fabricated but is created with repetition and consistency.

Raising roofing panel sub-assemblies at the multipurpose building at Bannon Creek School for the Natomas Unified School District in Sacramento, CA

 

Prefabricating sub-assemblies requires a high level of coordination and collaboration during both design and construction. It creates efficiencies by limiting the number of components that are designed and constructed, especially in unique conditions that may only occur in a single location. It also increases productivity due to the repetition in the fabrication of these components. This is further realized if components can be fabricated off-site where weather is not a factor, as inclement weather can cause delays.

Ultimately, the two major driving factors of implementation are schedule and cost.  Prefabrication of building elements off-site allows for a more predictable schedule. It also allows for a non-linear construction sequence, where the walls can be fabricated when the foundations and structural elements are being constructed. Then, roof panels can be fabricated as the walls are erected to be ready for installation upon completion. Properly executed, this process can limit the amount of work conducted on-site, and the close coordination of on- and off-site work can accelerate schedules and provide great savings in construction cost and time.

 

CASE STUDY

Studio W Architects was selected by Natomas Unified School District to design the conversion of three existing elementary schools into K-8 campuses, by expanding the sites and augmenting them with facilities and amenities for grades 7 and 8. We designed a multipurpose building that included a standard classroom and laboratory, which was site adapted at all three schools.

The need for classroom spaces varied by site. As a solution, we standardized a classroom building, which was modified to include five classrooms at American Lakes School and seven classrooms at Jefferson School. These buildings maintained standard elements, dimensions and volumes in both iterations. They also met the programmatic goals of providing standard classrooms, laboratories/STEM rooms, restrooms and intervention spaces.

The repetition we incorporated into the design proved to be effective throughout the entire process. We were able to discuss the project with the Division of the State Architect (DSA), the governing body by which school facilities in California are approved, and arrange for a single plan checker to review the project to ensure the approved buildings did not vary by site. This allowed for a good working relationship with our office, our engineers and DSA.

 

Standardized Buildings for Natomas Unified School District’s K-8 Conversions

 

Multipurpose Building

Classroom Building

American Lakes School

16,500 SF

8,500 SF

Bannon Creek School

16,500 SF

N/A

Jefferson School

16,800 SF

11,500 SF

(plus 7,500 SF of modular classrooms)

 

The site adapted building designs also allowed for equity among the school sites. All these schools now have the same multipurpose building and classrooms for their expansion to serve a K-8 student population. This also extended to the site work, with the addition of track and field facilities and play structures at each campus. School colors and mascots were incorporated at each to provide identity, individuality and character.

We worked closely with the contractor during the design phase to ensure we were providing the ideal conditions for preassemblies. We set the structural grid to allow for wall and roof panels to be prefabricated. We also standardized door and window types, casework, acoustic panels and tackable surfaces.

As we wrap up construction this summer, we are very excited about the finished product. We are happy to deliver a beautiful project. A project that was delivered both on time and within budget utilizing the elements of non-volumetric construction and preassemblies.

Examples of site adapted buildings with standardized elements for Natomas Unified School District’s K-8 Campus Conversions

Top: Multipurpose Buildings at Jefferson School and Bannon Creek School
Center: Classroom Buildings at Jefferson School and American Lakes School
Bottom: Gymnasiums at American Lakes School and Bannon Creek School

 

Blog post authored by Chris Garcia, Senior Project Manager