LAYER III

Rising from the Existing: The Architecture of Vertical Extension at Tôn Thất Thiệp Apartment

Bachelor Thesis with Distinction

Advisors: Prof. Arianne Wiegner & Prof. Lucio Nardi

Saigon Ward, Ho Chi Minh City

Summer, 2026

Layer I - The original 42 Ton That Thiep

Layer II - The first extension

Layer III - The second extension

However, the renewal of old apartment buildings has remained a persistent challenge. Despite numerous redevelopment proposals, implementation has often been delayed by structural limitations, financial difficulties, resident relocation, and conflicts between conservation and development interests. Consequently, demolition is regarded as the most practical solution. While redevelopment may improve building safety, it can also result in the loss of historically and culturally significant urban fabric. The replacement with isolated high-rise developments may weaken established communities and create abrupt spatial contrasts within the existing cityscape. This project investigates vertical extension as an alternative to demolition, using the 42 Tôn Thất Thiệp Apartment Building in District 1 as a case study. Rather than replacing the existing structure, the proposal retains, reinforces, and functionally adapts it while introducing a lightweight vertical addition above. The renovated building accommodates retail spaces and accessible housing for elderly residents and people with mobility limitations. The new extension provides public spaces and affordable housing for young people and low-income residents. By combining preservation and transformation, the project proposes a more socially inclusive approach to urban renewal.

District 1 has been long functioned as the commercial, administrative, and social heart of Ho Chi Minh City and remains one of the most intensively developed urban areas in Vietnam. Over several decades, rapid urbanization, population growth, and increasing land values have placed considerable pressure on its existing built environment. New commercial towers, luxury residential developments, and large-scale infrastructure projects continue to reshape the district’s skyline. At the same time, these processes have contributed to increasing urban density, inadequate housing conditions, and a shortage of accessible public and communal spaces. Within this changing urban landscape, old apartment buildings constitute an important yet increasingly vulnerable architectural layer. Constructed between the 1950s and the 1980s, these buildings include former French colonial apartment blocks as well as collective housing developed during the early socialist period. Although many are now physically deteriorated, they continue to support complex networks of residential, commercial, and social activities. Their corridors, balconies, staircases, courtyards, and ground-floor shops have evolved beyond their original functions, becoming active spaces of everyday life and contributing significantly to the identity and collective memory of the city.

Building parameter

Location: 42 Tôn Thất Thiệp, Saigon

ward, Ho Chi Minh City, Vietnam

Site area: 3,099.50 m²

Street right-of-way width: 20m

Site function: mixed-use

(residential & retail)

Historical image of the Tôn Thất Thiệp Apartment Building

The original apartment building was built with 2 stories; however, it was later expanded by adding an extra level to respond to growing functional demands over a period of time. This past intervention demonstrates that vertical extension is not an unfamiliar or imposed strategy but an approach already embedded in the building’s architectural evolution.

Design methodology

Conceptual model

The both-and of heaviness and lightness, compression and tension, and light frame and heavy core.

1 massing + 2 inner circulations

2 massings + 2 inner circulations

1 massing + 2 outer circulations

2 massings + 2 outer circulations

Mirroring the existing roof

Form variations

A new soft roof for the new volume

Replicating the existing roof silhouette

A new roof split and shifted above the volume

Conceptual drawing variations

Detailed urban context of new District 1 highlighting old apartment buildings

Conceptual model

Over the 42 Ton That Thiep Apartment

Structural diagram

The intersection space between the old and the new extension acts as a community public space for people