Whole-Building Renovation of a Showa-Era Retro Building | Okayama Building｜Yoshihiro Yamamoto Architects Associates

Yoshihiro Yamamoto Architects Associates

Renovation of a small mixed-use building originally constructed in the early 1970s.

Approach. The existing electrical meter board was repainted and repurposed as interior signage.

The deteriorated building nameplate was repaired and the retro typeface reconfigured.

A brick wall separates the approach from Unit 101. Bricks salvaged from old Shanghai houses were reused.

The antique bricks were pointed with mortar in three times the usual thickness to achieve a deeply recessed texture.

The stairwell walls are painted the project’s theme color, royal blue.

The existing fire shutter was retained to create vertical shaft fire compartments for corridors and stairs.

Visual separation between Unit 201 and its neighbor is achieved with wood blinds.

Overall view of Unit 201. Substantial mansard-form seismic braces give a sense of weight. Window frames were also replaced during this renovation.

Seismic standards were met by reinforcing the ground floor in RC and the second floor with steel framing.

Third-floor common area. Existing P tiles removed from the floor, walls repainted, ceilings left as exposed concrete.

Common-area design—often neglected in multi-tenant buildings—matters for tenants who receive visitors.

Unit 301. The state revealed by removing each room’s floor and wall finishes is unique in every case.

Unit 302. P tiles were removed, surface irregularities leveled with mortar, and the floor finished with a coating material.

Room nameplates were fabricated from blackened steel plates with brass cut letters for the room numbers.

Phase 2 construction. The former rooftop outdoor-unit platform was transformed into a rooftop garden; the south side, separated by a penthouse, provides seated areas.

Phase 3 construction. The deteriorated exterior was fully inspected and repaired, and new tiles were inserted.

Careful consideration was given to compatibility with the existing small-edge flat tiles; four color variations × three surface finishes were mixed and applied.

Yohei Sasakura

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A small mixed-use building constructed in the early 1970s. The owner inherited responsibility for the building’s management but, after decades of minimal maintenance and continuous exposure to the elements, the property had deteriorated and vacancies had increased, forcing a need for decisive intervention. When consulted, major housebuilders and contractors proposed demolition to create a parking lot or redevelopment as rental apartments. The owner resisted the notion that a concrete building must be torn down after only around forty years and, having sentimental ties to the building—he had witnessed its original construction as a child—preferred to explore rehabilitation. After an initial site visit, the project commenced.

The building was largely vacant, occupied only by a few long-term office tenants and a nearby construction site using part of the building as a temporary office. Interior alterations and patchwork repairs over many years had left the spaces in a chaotic state both aesthetically and in terms of compliance. Building services had deteriorated and wastewater odors were apparent. Although demolition would have been the most straightforward option, the simple structural frame was adaptable, and existing iron fittings and exterior tiles with irregular firing marks—materials rarely seen today—offered potential architectural value. The team agreed the building was worth salvaging and proceeded with a whole-building renovation.

Leasing strategy is paramount in commercial redevelopment, but conventional real-estate firms tended to appraise properties only by location and floor area, unable to communicate the appeal of an older building located a little farther from the station. We therefore partnered with an online-focused real-estate company and experimented to develop an optimal program that would attract a creative tenant mix. The final scheme comprises: a large rentable space, storage and bicycle parking on the ground floor; a variety of large, medium and small rentable units and a communal lounge on the second and third floors; and a SOHO unit on the fourth floor that can be occupied as a residence.

On the design side, we conducted a comprehensive as-built survey and undertook painstaking repairs that preserved durable original materials wherever possible. Structurally, weaknesses identified in the seismic assessment were reinforced with steel brace frames and reinforced-concrete walls, balancing interventions with the building’s aesthetic. On the building-services side, all wiring and piping within the building were replaced, and fire compartments, total floor-area calculations and firefighting equipment were rationalized to comply with the Building Standards Act and the Fire Service Act.

Construction proceeded in phases: Phase 1 (2014–2017) comprehensively updated interiors; Phase 2 (2017–2018) converted the rooftop outdoor-unit platform into a communal terrace; Phase 3 (2020–2021) carried out a full inspection and repair of the deteriorated exterior, removing sparsely detached and cracked tiles and inserting new accent tiles. Gradually the building reached a practical completion. During this period a variety of tenants—from web and architectural designers to antique dealers and apparel firms—moved in, activating the building. The owner now maintains a small attic-like room and enjoys the place personally. By addressing the intermittent issues typical of older buildings and incorporating tenant feedback, the property has become increasingly attractive over time.

Structure/Scale: Reinforced concrete construction, 5 stories; Use: Offices and multi‑family residential; Site area: 50 tsubo [160 m²]; Total floor area: 150 tsubo [500 m²]; Construction floor area: 190 tsubo [620 m²]; Design supervision: Yoshihiro Yamamoto [YYAA]; Structural engineering: Ooishi Structural First‑Class Architect Office; Contractor: Mitoma Komuten; Rooftop design: Takeo Matsushita [soji]; Real estate consulting: Osaka R‑Real Estate; Hardware/metalwork: Jozu Workshop

Introducing Whole-Building Renovation of a Showa-Era Retro Building | Okayama Building, an example of Architect / Design office facility architecture in 302, Zeniya Honpo Main Building, 14-6 Ishigatsujichō, Tennōji-ku, Osaka by Yoshihiro Yamamoto Architects Associates.