How Modular Construction Keeps Housing Projects Affordable And Sustainable

Washington’s affordable housing crisis has reached a breaking point. The state’s Affordable Housing Advisory Board is calling for the construction of 1 million new residences within the next two decades, with half of them built for households making less than 50% of the area median income.

Within this time frame, King County, the state's most populous county, is in need of 308,000 homes, with 195,000 of those being affordable homes for its approximately 2.3 million residents.

To answer this urgent need, construction management and general contracting company Synergy Modular teamed up with King County, Catholic Housing Services and Bazan Architects Inc. to develop Saint Margaret’s Place in Shoreline, Washington.

The affordable housing development, which totals 72K SF, encompasses four levels of 100 units and commercial real estate for lease on the street level, as well as commercial office space housing both resident services and community service providers.

Saint Margaret’s Place was built using volumetric modular construction, a technique in which modules are joined together in an off-site factory and are stacked at the construction site instead of being built on-site. This project encompassed 80 modules of different lengths, which decreased the building’s scale while simultaneously fitting more residential units within the square footage.

Synergy Modular CEO Justin Stewart said that despite the regulatory hurdles and obstacles that arose during construction, the project was completed within 14.5 months and for less than $265K per unit.

He said that demand for modular construction has been increasing since Synergy Modular was founded in 2017, especially within the affordable housing sector. When components of the building are constructed both on and off the site simultaneously, the time spent on construction is accelerated, thereby saving time and reducing the cost associated with labor and materials.

A 2019 McKinsey & Co. report found that modular construction methods may achieve a 20% cost reduction. 

“You can build affordable housing using modular at a considerable cost savings compared to site-built,” Stewart said. “Modular construction is not something off in the future that will happen someday or is coming soon. It’s already happening with regularity.”

Stewart said modular construction also allowed the Saint Margaret’s Place project to meet stringent sustainability requirements imposed by the state’s Evergreen Sustainable Development Standard, which is one of the aspects that can drive up the cost of low-income housing tax credit projects. Synergy Modular met these requirements without much of an increase in its construction costs.

Using modular construction also provided environmental benefits.  

“Factory construction optimizes material usage in the assembly process to eliminate waste,” Stewart said. “In addition, you’re constructing a building that’s going to perform as well or better than traditional buildings designed for energy efficiency.” 

Stewart said the building’s location presented a challenge. The substantial slope of the site required a 20-foot-plus shoring wall to be installed underneath the highly trafficked Highway 99, which added to the construction cost and schedule. Synergy Modular also installed tie-ins for the property’s utilities under the highway as well as two levels of post-tensioned concrete to enable the property to sit above street level. 

Another challenge arose when Synergy Modular had to find a different modular supplier one month before modular building was set to begin. Through its network of subcontractors, it identified NRB Modular Solutions as the supplier that could fabricate the units without affecting the time frame and cost.

In January 2023, seven-and-a-half months after the project commenced, the modular units were installed atop the foundation with cranes amid seasonally rainy weather. The project was delivered seven months later with units open for occupants to rent.

“Modular construction requires a deep level of coordination and collaboration among ourselves, the developer, the factory, the design team and the subcontractors before and during the project,” Stewart said. “We had to collaborate in person to ensure quality assurance and quality control with the factory up in Canada throughout the entire production.”

Stewart added that the Saint Margaret’s Place project is an opportunity to demonstrate that modular construction has matured to be a viable tool to combat the affordable housing crisis in high-cost areas.

This article was produced in collaboration between Studio B and Synergy Modular. Bisnow news staff was not involved in the production of this content.

Studio B is Bisnow’s in-house content and design studio. To learn more about how Studio B can help your team, reach out to studio@bisnow.com.