The Insider: Architects Rebuild Sinking Park Slope Brownstone and Add a Penthouse

One thing Douglas Segulja has learned from years of architectural practice is this: “Never take the initial call at face value. The project often grows into something entirely different.”

That’s what happened with this turn-of-the-20th-century brownstone, which had such serious structural issues it needed a down-to-the-shell gut. A pair of longtime homeowners who’d been living on the two lower floors of their building called on Segulja and Margot Otten, his partner in Brooklyn- and Hoboken-based OSSO Architecture, to expand their living space when the birth of twins grew their family from three members to five.

“They had rental units on the two floors above and had always talked about expanding up,” Otten said. The floors in the owners’ duplex been leveled, but “the slope of the floors in the rental units was incredible–you felt like you were on a boat.” The architects knew they’d have to at least replace all the upper floor joists, but the clients were also interested in adding a story, with the additional load that entails. “That’s when we looked into the foundation, found out the building had settled, and what our options were for stabilizing it,” Otten said.

Turns out the house had been built on a 25-foot-deep pit of coal ash and was sinking significantly from front to back, requiring substantial structural intervention. Step one was driving 32 helical piles, or metal columns, forty feet into the ground beneath existing foundation walls to reach a solid base. Then interior demolition proceeded until only the front facade and party walls were left standing.

OSSO Architecture reimagined the interior with an emphasis on wood, mostly oak, per the clients’ request. The floors are oak, with radiant heating beneath. The all-new central staircase is wood, with hand-carved oak handrails. Windows and sills are wood as well. There is extensive custom millwork throughout by KF Restoration, the general contractor.

The now five-story townhouse has guest space and storage on the garden level, a sitting room, dining and kitchen on the main floor, a primary suite and family room on the second, kids’ bedrooms and a home office on the third. Atop it all is a spectacular new rooftop penthouse for family living and entertaining, with landscaped terraces on each side.

OSSO Architecture replaced a crumbling brick stoop that was not original to the house with bluestone treads, open risers, and a steel railing. They cleaned up the exterior facade, installed new Pella windows, and restored the original front doors, now boldly painted Exotic Purple by Benjamin Moore.

The architects added a small vestibule with an oak door for another layer of weather protection. They introduced wide curved openings between rooms “to go along with the curves of the new stairs,” Otten said.

Stairs on the lower levels have solid oak risers and treads. “We wanted them to feel grounded, like a townhouse stair,” said Otten. “It transitions to more of a floating stair at the top, very open so light comes through.” Oak spindles downstairs change to steel on the upper levels, but the hand-carved oak rail is “one long sinuous line,” as Otten put it, from top to bottom.

Hidden in the kitchen’s wall of cabinetry is a powder room with a custom sink of Calacatta lilac marble.

Planes of fixed glass, with two doors, make up the new back wall on the parlor level.

The Blue Star range was ordered early on in the process. The kitchen millwork, all custom, includes a marble-topped island with storage on one side and seating on the other. Glass pendant lights by Pablo Glass, out of Woodstock, hang above.

Positioning the new staircase in the middle of the building, with large skylights above, brings light deep into the house.

Vertical grain oak uniformly clads new closets and other built-ins in the primary bedroom. The exceptionally deep window sills are the result of a thickened back wall, one of the ways OSSO Architecture addressed the slanting site condition.

The primary bath has a spa-like feel, with six-foot cedar panels wrapping the walls and a slate floor from Clé. A semi-transparent piece of glass in the ceiling above the Spoon tub from Agape brings light into the windowless space from the skylight two floors above. The floating vanity has a custom cast-concrete sink and custom medicine cabinets.

The last light-flooded flight of stairs before the roof, with open risers and steel balusters, “feels like you’re popping up to this more contemporary, brand new element,” Otten said.

The new penthouse, approximately 400 square feet, is flexible space for entertaining, working from home, and just hanging out. It contains a beverage fridge and small sink and dishwasher to enable easy clean-up.

The penthouse is pulled back from the facades, per zoning regulations, at both front and back. Tile-paved terraces on either side is the happy result, with plantings by Brooklyn-based Hannah Edmunds Gardens.

A cantilevered steel and glass awning on the Manhattan-facing side allows outdoor seating even when it rains.

The entire rear facade is new, with a stucco finish and Alu-clad windows from Pella. Aluminum spandrel panels between the windows cover the structural steel. “It makes the windows feel more continuous, instead of punched out,” Otten said.

[Photos by Erik Bernstein]

Got a project to propose for The Insider? Contact Cara at caramia447 [at] gmail [dot] com

The Insider is Brownstoner’s weekly in-depth look at a notable interior design/renovation project, by design journalist Cara Greenberg. Find it here every Thursday morning.

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