STACK by Johanjun Architects – A Sculptural Commercial Landmark in Seongbuk-dong, Seoul
Pencil House is a transformed office space featuring bright minimalist interiors, improved insulation, and a distinctive elongated façade resembling a pencil.
STACK, designed by Johanjun Architects, is a striking commercial building located in the culturally rich neighborhood of Seongbuk-dong, Seoul. Completed in 2025, the 105 m² project stands as a modern architectural intervention in an area known for its traditional homes, historic sites, and the tranquil atmosphere that contrasts with the hyper-dense urban fabric of central Seoul.
A Site Rich with History and Urban Texture
Seongbuk-dong, once lined with the residences of literati, artists, and prominent figures, still carries the layered memories of its past. The architects were already familiar with the site, passing it frequently after relocating their own office to the neighborhood. The plot, perched on a sloping terrain and formerly hosting a house later converted into a small commercial facility, presented both challenges and opportunities.
The steep topography, stone retaining wall, and proximity to the road required careful structural planning. Despite the risks associated with excavation and civil complaints, the architects embraced the project as an opportunity to create a building deeply rooted in its context.
Design Inspired by Bedrock and Urban Visibility
Because of its high visibility from Seongbuk-ro, one of the main roads in the area, the building needed a memorable façade. Johanjun Architects chose exposed concrete with a vertical pattern, evoking the feeling of a monolithic form carved directly from the mountainous bedrock of Bukhansan.
The site's geology made basement construction difficult, but direct road access was a major asset. The architects combined functionality with sculptural expression, maximizing the commercial appeal of the building while adhering to zoning and daylight regulations.
Dynamic Massing and Regulatory Constraints
The northern side of the property faced tight restrictions due to North-Facing Daylight Regulation (Jeongbuk Iljo). To translate this required set-back into a visually expressive form, the massing steps forward from the third floor upwards. This stacking effect creates tension and movement on the façade, making the building stand out from the street while subtly navigating the legal conditions.
A Personal Memory Hidden in the Architecture
One of the most unique aspects of STACK is a personal homage embedded within the design. The previous building had housed a beloved local burger shop, Yum Yum Burger, which the architect often visited. As a quiet tribute, he incorporated subtle rounded forms reminiscent of stacked burger buns into the façade. Although this story was never revealed to the client, it adds emotional depth and narrative meaning to the project.
Efficient Construction and Urban Craftsmanship
The building’s exterior softens at the corners, allowing the façade to wrap seamlessly across surfaces. Inside, clean and minimal design choices ensure flexible use for future tenants. Despite construction challenges—from sloped conditions to neighborhood constraints—the project was completed safely and successfully, earning the client’s satisfaction and adding a contemporary landmark to Seongbuk-dong.
STACK embodies the spirit of Seoul’s evolving urban landscape, where memory, history, and modern architectural expression come together in a compact yet impactful structure.
All the photographs are works of Mongsang
