Residential

SK&A provided structural engineering services for this 11-story, 325-unit, multifamily residential apartment building. Located on a former part of the Navy Yard, the project included approximately 20,000 sf of retail space as well as two courtyards, a rooftop pool, and a small green roof.  The building sits atop a three-level, 110,000 sf below-grade structured parking garage for 250 cars and has a landscaped plaza on the garage roof slab at grade level.

At the northern end of the building, two existing sewer lines cross the site. Located just below the B1 level, the first of the two sewer lines is a 6-foot diameter, 100-year old masonry sewer that crosses the entirety of the east-west footprint.  The sewer had to remain active during construction and the ability to access this line in the future was mandated by the utility. Drilled shaft foundations were used to support the building on either side of the line, circumventing the sewer and maintaining the required clear distances.  A structured slab-on-grade was used above the line, spanning to the adjacent drilled shafts while imposing no additional loads on the sewer from occupancy use.  Additionally, this slab was designed to allow for a 10-foot section to be removed for future maintenance of the line while the larger area of slab continued to provide support for the primary building structure.

The CSX East development located in the Capitol Riverfront neighborhood of Southeast, Washington DC, consists of two residential buildings (Illume) and one hotel building (AC Hotel Capitol Hill).  The development includes pedestrian bridges that connect all three buildings, with the most striking bridge connecting the AC Hotel Capitol Hill’s 11th floor to the existing ORE 82 Eye apartment building.  Standing over 100 ft. above the ground level, the bridge facilitates guests’ access to the amenities offered by the two buildings, without imposing any additional loads on the existing building.

The biggest challenge in the development of the design of the bridge was to ensure no additional loads were imposed on the existing ORE 82 Eye apartment building.  To achieve that, the bridge had to cantilever ~20 ft. off the new building, and safely transfer the loads to it.  Eight attachment points were located on the structure where the bridge’s structural framing can attach to.  The bridge and its roof, made of wide flange beams and tube column sections, connect to the 11th and 12th (roof) levels, respectively.  Under the bridge, a set of steel tube braces are provided to transfer loads to the 10th and 9th floors to reduce the true cantilever.  

Situated at the top of the up-and-coming Union Market District, in Northeast, Washington, DC, 440 Penn is a new 13-story, 305,230 sf residential building featuring 23,000 sf of ground floor retail and three levels of below grade parking (80,000 sf). The building is surrounded by historic low-rise buildings providing unobstructed views of both the Washington Capital and Monument.  In addition, it was critical to the neighborhood and zoning requirements to respect the history of the area while bringing it into the future.

The design team was tasked with maintaining the building’s exterior character and provide a seamless integration of the new residential building on the west side while not disturbing the current tenant on the east side.  To maintain this seamless integration, the two-story existing historic façade was to remain and incorporated with the new building. The existing façade had to be temporarily supported during construction to allow for the new building to be constructed behind it.  

Press House Warehouse is a new mixed-use complex located in Northeast, Washington, DC and surrounded by several urban amenity-rich neighborhoods such as Union Market, NOMA, and Shaw.  The 462,511 sf building features the historic retrofit and renovation of the existing building at 301 N Street, NE, a warehouse designed in 1931 for the National Capital Press.  The historic press building is a three-story building consisting of two levels of conventionally reinforced, two-way concrete slabs, with the roof comprising of a series of steel monitor trusses spanning between girders supported on built-up steel columns.  

The repurposed building is also used for office and ground level retail, while rental units were added between two new high-rise structures over two levels of below-grade parking.  Hickok Cole Architects currently occupy office space at the 2nd and 3rd floors of the newly renovated historic building.  SK&A served as the engineer of record for their office fit-out, which included cutting an additional large opening for an interconnecting stair.   

Located in the Capitol Riverfront’s Ballpark District, 1000 South Capitol Street is a 13-story, 350,000 square foot U-shaped residential building with 244 apartments, 14,000 sf of retail space, and a 225 space below-grade garage.  The rooftop features a resort-style deck with an infinity-edge pool, cabanas, and lush landscaping.  Additional amenities include a fitness studio, wine bar, courtyard gardens, podcast studio, screening room, billiards room, and pet spa.

A structure of architectural beauty and engineering excellence, the building features dramatically angled floor-to-ceiling windows, a landscaped terrace over the rear portico, and numerous cantilevered balconies.  The building design utilized an undrained (bathtub) basement, supported by auger cast pile foundations, and hydrostatic slabs with integral pile caps.

Previously constructed as a seven-story cast in place parking garage, the new vertical expansion of 161 Peachtree Center in Atlanta, GA included two new parking levels and 18 floors of residential units.  Originally designed in 2001 for a future 12-story office building, the new developer acquired the current building with the intent of revising the future office tower into a residential building.  The main issue is an existing office structural frame layout was not conducive to a modern residential building.  

Tower only columns were introduced to reduce the span and minimize the slab thickness to eight inches max.  This allowed for shorter floor to floor heights and reduced the weight and height of the structure.  Since tower only columns could not extend below to foundations due to the existing parking garage drive aisle and parking layout, large 8’-0” deep bonded post-tensioned transfer girders were introduced at the interstitial 14th floor.  Similarly to the tower only columns, the tower only shear walls could not extend below into the existing parking garage.  The shear walls had to stop at the 14th floor transfer level, which created a vertical irregularity within the lateral system.  Nine-foot-tall bonded post-tensioned transfer girders were used to transfer the shear wall gravity and lateral loads to the surrounding columns and diaphragm.  

Situated on the edge of the Potomac River, the Wharf Parcel 8 also known as the Tides Apartments and Pendry Hotel, pushed the boundary of sloped buildings.  With 13 stories of hotel on the west side and 13 stories of residential units on the east side, the U-shaped building creates unobstructed views of the Potomac River for both functions.  This was imperative to the architectural design of the building. 

Located directly over the underground METRO green line tunnels, the new foundations needed to adhere to the strict requirements of the Washington Metropolitan Area Transit Authority for building overtop of an existing operational tunnel.  A hybrid system of a mat foundation and spread footings were used to help reduce the surcharge on the tunnel below as well as create an economically efficient design for the foundations.  Noise and vibration from the tunnel below were also a concern.  An isolation pad under the mat foundation, spread footings, and columns were used to mitigate any noise and vibration from the tunnel below that would propagate through the first several floors of the building. 

The Skyline Towers residential apartment building complex features two (2) twenty-six story cast-in-place concrete structures each with penthouse amenity spaces.  An initial roof condition assessment, which included roof cuts of the main roof and penthouse amenity roofs, revealed that the original roof membrane had failed and was concealed by a global application of single ply modified bitumen membrane.  Due to a lack of original drawings, Ground Penetrating Radar (GPR) scanning and exploratory demolition of the South Tower’s main roof slab was done, to model and analyze the structural capacity of the slab to support the new proposed roof terrace loads. Following the roof condition assessment and structural analysis, the roof areas were prioritized for replacement and the South Tower main roof and penthouse amenity roofs were selected to be replaced ahead of other renovations planned for the apartment buildings.

The penthouse amenity roof replacement scopes were designed, bid, and executed by a qualified local roofing contractor with the work completed in phases while the building remained occupied, and the amenity spaces were under renovation.  Each amenity space roof assembly was removed and replaced with a multiple ply modified bitumen roof assembly.  New air barrier, rigid insulation, coverboard, liquid-applied flashings, and sheet metal flashings were installed. Isolated concrete repairs were also completed throughout the penthouse screen wall enclosure. Structural analysis and strengthening of the existing roof joists were also completed for the installation of new rooftop equipment units for the penthouse HVAC improvements.  

SK&A’s Repair and Restoration Division performed a detailed survey and evaluation of the roof areas for the apartment building located at 4903 Edgemoor Lane in Bethesda, MD.  As part of the survey, the original architectural and structural drawings were reviewed as well as maintenance reports for the building.  The roof areas were then visually inspected in order to evaluate the condition of the single-ply PVC membrane assembly and to observe the condition of the flashings, terminations, and overall quality of the roofing construction.  

The building roof, which was original to the building, was recommended for complete removal and replacement with a new two-ply SBS modified bitumen membrane adhered to the concrete roof slab in an inverted roof membrane assembly (IRMA) configuration.  The new roof assembly design also incorporated fleece reinforced PMMA liquid flashings and increased insulation to meet new energy code requirements.  As part satisfying Montgomery County’s “green space” requirements, the roof replacement was designed and detailed as a green roof assembly.  

SK&A provided structural engineering services for the addition of new buildings and the renovation of an existing facility at the 14-acre Ingleside Retirement Community Campus in Washington, DC.  Located adjacent to Rock Creek Park at 3050 Military Road, NW, the non-profit retirement community’s current site was originally established in 1960.  The new changes to the site consist of:  

• A new independent living facility (120,000 sf) with 90 units, a new assisted living facility (50,000 sf) with 15 residences, and structured parking (60,000 gsf).  The two residential buildings will connect to each other as well as existing buildings at the site.
• A new skilled nursing and memory support facility (100,000 gsf), plus structured parking below (44,000 gsf).
• A new independent living commons, renovation of the existing commons, as well as overall sitework (15,000 gsf).  The new commons or “Center for Healthy Living” will contain multiple amenity spaces, including a salon/day spa, classrooms and art studios, cafe, yoga and aerobics studio, technology center, meditation room, and fitness center.