A Hidden Penthouse Sits Atop a Historic Cast-Iron Building in New York

A Hidden Penthouse Sits Atop a Historic Cast-Iron Building in New York

By Anna Squier
Located in Tribeca, this residential development consists of a complete renovation and new construction—both concealed behind one of New York's historic cast-iron facades.

Taking its name from a hidden rooftop addition that contains a three-story penthouse, The Stealth House by New York-based WORKac is unassuming when viewed from the street, through dramatically-modified, modern residential spaces dwell behind the facade. Due to strict city requirements, any rooftop addition to the historic structure was to be invisible. This called for a strategic analysis of the site and corresponding cones of view, resulting in the sculptural, angular form of the addition. 

This diagram shows the cone of vision from the furthest point from which the building is visible. 

The 1857 facade was completely restored with a new charcoal color that references the building's history.  In collaboration with artist Michael Hansmeyer, new versions of the original Corinthian column capitals were created through 3D modeling. 

Earning the nickname "The Obsidian Building," the charcoal gray facade conceals the penthouse and modern renovations from the street level. 

A detail of a new column capital reveals how historic proportions were replicated through new technology.

On the interior, the designers combined new concepts of urban living with nature-inspired elements. Murals of trees created from mosaic tiles line the bathroom walls. Each of the single-floor units has built-in composting, an herb garden in a four-foot tall "bonsai" space above the kitchen, and a fern landscape connected to the master bathroom, watered by steam from the shower condensing on the glass enclosure. 

An isometric drawing demonstrates the "bonsai" space, complete with seating and an herb garden, perched above the built-in storage and kitchen. 

A fern living wall encloses the shower. 

The penthouse combines sleeping spaces and a family room within the original fifth floor of the building. Entertaining and dining areas fill the space under the new angular roof perched atop the highest floor.  Outdoor spaces are hidden behind the original pediment, while a hot tub fills a repurposed elevator bulkhead. 

Entertainment and dining spaces sit below the angular roof in the penthouse. 

The penthouse space extends across three floors, creating a unique urban form of living with integral vertical circulation. 

The former elevator bulkhead has been repurposed into a hot tub. 

The secluded terrace is hidden behind the building's pediment. 

At a distance, the design appears simple, but upon closer view, the elements of modern intervention and new contemporary design come to focus. 


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