Revitalizing downtown Raleigh, one building at a time

The Dillon is an 18-story, mixed-use project on 2.5-acre city blocks with three buildings — two residential and one office building.

Stewart helps plan and design its new headquarters in a landmark building.

Frequently recognized as a top city on “best of” lists for places to live and work, such as Best Places to Live by U.S. News & World Report, the city of Raleigh, N.C., continues to grow year over year. In fact, Raleigh and its surrounding area in Wake County added an estimated 63 residents per day in 2017. With Raleigh’s rapid rise has come a revitalization of the downtown neighborhoods and buildings, bringing more places to live, work, and play within the city center.

In recent years, much attention has turned to the Warehouse District, a rapidly expanding and vibrant area in downtown Raleigh. Optimizing development efforts in the area is The Dillon, the first mixed-use development of its kind in the district. First conceptualized in 2015, the project has become the landmark for the area and has forever changed downtown Raleigh’s skyline.

Behind the scenes of The Dillon

The 18-story mixed-use project is a Kane Realty property located on 2.5-acre city blocks with three buildings — two residential and one office building — including a total of 214,000 square feet of office space and 40,000 square feet of retail and restaurant space.

The two residential buildings consist of wood-framed construction supported by a composite steel-framed podium slab and include a total of 260 units with easy pedestrian access and central parking. The residential buildings also feature a wood sundeck with a pool and two outdoor courtyards.

The office building, featuring post-tensioned concrete construction, includes a preserved warehouse façade with an open-air portico, ground floor retail, 980-parking-space cast-in-place parking garage, and an eight-story office building tower with a public roof terrace on the 9th floor, overlooking vibrant downtown Raleigh.

An engineer’s dream:

Design your own headquarters

In June 2018, Stewart, an interdisciplinary design, engineering, and planning firm, relocated its headquarters to The Dillon. Before moving in, the firm had the unique opportunity to play numerous key roles in the planning and design of the landmark building that would later become its home.

With the hiring of Stewart’s landscape architecture, civil and structural engineering, geomatics, geotechnical, and construction services, the firm’s interdisciplinary collaboration helped streamline communication between practice areas and with partners, from the design phase through execution.

Originally built in 1914, the historic Dillon Supply Company sat as a vacated warehouse for many years before Stewart supported its renovation and modernization. Throughout the design process, Stewart was tasked with preserving the essence and historic value of the original Dillon Supply Company, while maintaining ties to the surrounding Warehouse District and downtown Raleigh area.

One key stipulation by the Raleigh City Council significantly impacted engineering and design of the building; the original Dillon Supply Company signage on the façade was to be preserved on two sides of the office building. The design team agreed that beyond the requirement, keeping parts of the original façade felt right for the project as it sought to tie the property into the history of the Warehouse District while ushering new technology and industry into the area.

To preserve as much of the historic building and its relics as possible, Stewart’s geomatics practice area used 3D laser scanning technology to map the exterior and interior of the original building, capturing all the existing data in an easy-to-reference 3D model.

The structural engineering team then used that information to identify how to preserve the façade in a way that would maintain the unique personality of the former warehouse while reinforcing the existing infrastructure. Using calculations from the 3D model, the façade measured a full 2 feet thick. Preserving this structure required temporary bracing with columns set back from the wall at the lower level to allow contractors to reach the foundation while the building was under construction. Deep transfer beams were then required to support the seven stories of parking over this level.

Other salvaged artifacts and parts of the original building were identified within the 3D model and repurposed throughout the design of The Dillon. Stewart’s planning and design team identified a crane and castellated beams which they later used in the property’s most popular outdoor spaces, including the 9th floor public terrace. Castellated beams serve as a trellis over the portico, 9th floor terrace, and residential courtyard. Swing-arm cranes once welded to building columns and used to move heavy materials from one bay to the next, now hold lighting elements.

Engineering ingenuity

Additional regulations set by the City of Raleigh helped facilitate a further dose of creativity and engineering ingenuity from Stewart. That’s because the 9th floor public terrace, the entrance portico, and other outdoor features are more than just aesthetically pleasing features of the building. They allow The Dillon to meet the City of Raleigh’s open sky regulation (a.k.a., amenity area) dictating that 10 percent of a project’s usable space must have open sky above it.   

While it may be challenging to accommodate these features on a skyscraper in the middle of a downtown area, it can also offer additional engineering opportunities. Stewart’s planning and design team took advantage of the space, layering multiple uses for the same area. The portico is the main entry to the building and is also the amenity area, and the permeable pavers serve as the stormwater control measure for the property.

In downtown areas, it is especially important to layer multiple uses wherever possible to create an efficient use of high-cost land area. Leveraging soil infiltration rate data collected during tests by the firm’s geotechnical and construction services team, the front portico surrounding The Dillon signage façade was designed to ensure safe water runoff and prevent flooding at its main entrance. The final design consists of several customized permeable layers. The top brick layer design is a permeable paver filled with washed stone, followed by multiple layers of washed stone.

In addition to requirements from the City of Raleigh, Stewart collaborated with two architectural partners on the project — Duda Paine Architects on the office building and JDavis Architects on the two residential buildings — as well as property owner Kane Realty. With strategic collaboration, Stewart served as the common structural engineer, civil engineer, and landscape architect for both properties, blending the vision of the two architects together to produce a final product with an intentional design. Known throughout the region, each of these partners hold high standards for their work and the work of their consultants.

Where Duda Paine incorporated unique sloping walls into the architecture, Kane Realty idealized a further distinctive characteristic that every corner throughout the building would be column-free, increasing panoramic views and natural lighting. To mimic the sloping walls, Stewart’s structural engineering group engineered sloping columns to match the architecture while providing sweeping views of downtown Raleigh.

Part of the community

As a new landmark in the Warehouse District, it was paramount to make The Dillon feel like a natural addition to the neighborhood. That includes its surrounding roadways and sidewalks.

The City of Raleigh’s Comprehensive Transportation Plan clearly defines ideal paths for cyclists throughout the city. The Dillon lies directly on a main bicycle thoroughfare, connecting one side of the city to the other. Stewart’s planning and design team was intentional about the bike lane configuration to keep bicycle traffic flowing properly with lanes consistent with the city plan. Sidewalks were also designed to mimic what existed in areas on either side of the building, while maintaining a clean and understated look that would highlight the building.

Sometimes it’s the aesthetically unpleasing parts of a project that are the most challenging, yet important to consider. The sanitary system in downtown Raleigh is more than 100 years old in some places and was designed for a substantially smaller city. Stewart designed the replacement of all the sanitary construction connected to the building and upsized the main for a growing downtown community by employing a unique sanitary construction strategy. While pipes are typically replaced and installed with an open cut trench excavation, cutting into and removing existing pavement, this project utilized pipe bursting, a trenchless method.

A hole was opened on the street corner, sending an expander head into the existing pipe. The expander head consists of two components: a leading end designed to guide the equipment through the pipe, and a trailing end with four pneumatic arms to “burst” — or break — the pipe apart. A machine then pulls in a much larger new pipe. As in any downtown location, Raleigh has multiple utilities below the street including natural gas, telecommunications and storm drainage lines, power, water, and sewer all within a 60-foot space between buildings. This technique avoided the need to uproot or relocate any other utilities along the block, saving time and money.

Landmark change

Already making its name as an iconic property in downtown Raleigh, The Dillon’s intention to preserve the history of the district while ushering in a new era of technology firms, art museums, restaurants, and destination retail is evident throughout the execution of the building’s design, as well as the tenants moving in.

Stewart was not only the first office tenant to move in, but also the first to commit to The Dillon as its new home, well before the revitalization was underway. This forward-thinking decision is paying off, placing Stewart in the center of an entrepreneurial and pioneering atmosphere that matches its company culture.

The innovative and appealing design of The Dillon — merging old and new — is attracting a diverse array of retailers and new businesses to the Warehouse District. In addition to Stewart, technology firms and co-working spaces are quickly filling the office space. Urban Outfitters, Heirloom Brewshop, Weaver Street Market, and Barcelona Wine Bar are scheduled to open in the retail space.

Information provided by Stewart (www.stewartinc.com).