Prefabrication Enables Swift Construction at 20 Mass Ave in Washington, DC

Approaching a complex repositioning of a dated office building into an experiential, urban destination in Capitol Hill, DPR’s team engaged in a collaborative design and preconstruction phase to plan how this transformation would unfold. In the bustling neighborhood adjacent to Union Station and three blocks from the U.S. Capitol, the team implemented alternative solutions to traditional construction sequencing to minimize construction disruptions, enhance quality and ensure the safety of the local community and workers.

The existing 300,000-sq.-ft. building is being extended both vertically, adding three floors, and horizontally, increasing its total size to 427,191-sq.-ft. The mixed-use property will offer 183,515-sq.-ft. of Class A office with dramatic views, 14,500-sq.-ft. Penthouse amenity floor, 274-key Royal Sonesta Hotel, and 13,832-sq.-ft of ground-floor retail. A new curtainwall and panelized facade will be installed, two atriums will be cut into the existing structure, the building will be structurally enhanced and reinforced, and the roof was demolished in preparation for the new addition.

“During our initial preconstruction phase, we established that prefabrication, SurePods and DPR’s Self-Perform Work (SPW) team would enable the project to stay on schedule and minimize disruption to the local community,” said Matt O’Malley, Preconstruction Lead.

The exterior rendering of a mixed use complex
The future mixed-use complex will entail retail and restaurant space on the first floor, six stories of hotel, topped by four stories of office space, and a rooftop restaurant and amenity space. Courtesy of Leo A Daly

Prefabricated SurePods Ensure Consistency, Quality and Schedule Enhancements

As the team dug into the details of the project they saw an opportunity to engage SurePods, a prefabrication vendor, to build 211 bathrooms for the hotel. The factory-built custom bathroom pods, complete with high-end finishes, were manufactured simultaneously with the hotel’s construction phase, reducing the schedule by 10%. SurePods enabled the team to deliver predictable results by fabricating the repeatable, high-end bathroom design in a controlled environment. The fabrication process in factory setting took 42,700 hours, 100 hours per pod, enabling the team to take that time to focus on other scopes within the building.

“When issues have been discovered on the project, DPR has been a fantastic partner, coming to the table with multiple options to resolve with the pros and cons for each,” said Chris Cotter, Sr. Project Manager for The RMR Group. “This has been especially helpful during such a complex major building renovation where existing conditions differ from record drawings. Using these prefabricated bathroom pods helps with this effort to provide additional logistical control and ability to maintain the schedule and deliver on time for our clients and tenants.”

“To prepare the building for the SurePods installation, you need a clear space for the pod with MEP connections roughed in, but most importantly the floors have to be perfectly level,” said Kurt Sandberg, DPR Project Executive. “The DPR team employed virtual design and construction (VDC) to assess the floor levelness through heat mapping. Together our VDC and SPW teams analyzed the levelness, evaluating two options—leveling by floor or by individual rooms.”

The team concluded that leveling by room would allow the most flexibility for sequencing and allowed the team to address specific levelness issues in each room, along with a faster installation timeline. SPW crews installed concrete pads in each room, ensuring floor levelness creating the ideal conditions for setting each pod.

SurePods utilizes a nationwide installer but scheduling conflicts rendered them unavailable for this project. As a result, DPR’s SPW team stepped in to help, enabling the project to maintain its delivery and installation schedule.

“SurePods has been there throughout the installation to guide the SPW team through the installation, inspecting the quality and accuracy of the team. They’ve done a great job and kept the project on schedule. Using SurePods prefabricated bathrooms reduced the project schedule by almost 10%,” noted Charles Best, SurePods onsite supervisor.

SurePods bathroom installation in progress
The SurePods arrive completely finished on the interior, ensuring quality consistency for each and every room. Courtesy of John Baer Photography

20 Mass is SurePods’ entry into the Washington, DC market. As such, they invited the local community onsite to understand the benefits of implementing this unique solution on future construction projects. Nearly 50 industry partners and customers from various markets have toured the project and watched the installation of the pods. Vincent Ng from JLL commented, “Our industry needs to do more of this. This is changing how we work.”

SPW Innovates Solutions to Logistics Challenges

In addition to the SurePods installation, SPW has been instrumental in developing alternate solutions to accommodate public access to areas adjacent to the site and the challenging logistics of the urban environment. During preconstruction the team was planning for the façade replacement with a new curtain wall and metal panels, and they realized a significant challenge on the west elevation of the building which faced a narrow alleyway with an active loading dock and garage. Stick framing the west elevation, the traditional way to build this scope, would have significantly impacted the alleyway and other work being conducted simultaneously.

“We recommended prefabricating the panels,” said David Huff, DPR’s DC-Baltimore SPW Lead for this project. “VDC was engaged to model the west elevation panels and provide a visual depiction of the construction sequence to verify the feasibility of this approach. The model allowed the team to visually understand just how repetitive the process would have been if they had opted for the traditional stick build, and the efficiencies that prefabrication had to offer. The model was then used to produce shop drawings, expediting the ordering of materials.”

This meant all parties involved saw the value of prefabricating the exterior cold-formed metal framing (CFMF) panels, including the sheathing, air barrier and miscellaneous steel plates, to ensure safety, quality, and most importantly allowed the team to immediately mobilize and stay on schedule. The team used the site for laydown which allowed the SPW crews to prefabricate the panels on-site, and then immediately install them. This is the first time DPR’s local SPW crews have been involved with prefabricating any component of a project to this extent, let alone designing, assembling, and immediately installing on-site. The crew has now set all of the exterior metal panels, with multiple trades worth of work encompassed in one shot.

Exterior view of in progress build, pods being hoisted up the side of building
Approximately 20 pods per day were lifted and set in place. Each bathroom will be connected to the MEP systems, completing the bathroom installation process. Courtesy of John Baer Photography

Looking Ahead

The construction at 20 Mass continues with the team now shifting their focus on the curtainwall installation, cutting the atriums into the center of the building, and constructing the demising walls between guest rooms. The project is expected to deliver Spring 2023, around the same time the iconic cherry blossoms are in bloom.

A DPR SPW worker pays close attention as he assists with hoisting the CFMF panel into place.
A DPR SPW worker pays close attention as he assists with hoisting the CFMF panel into place. Courtesy of John Baer Photography
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