Local studio ODDO Architects has extended TH+ House in Vietnam, organising a series of shared, flexible spaces around tall voids informed by the "social intensity" of Hanoi's urban alleyways.

The project saw ODDO Architects returning to the site of TH House, which it completed in 2021, to expand it into a neighbouring 2.5-metre-wide plot for the client's growing family.

ODDO Architects has extended its TH House in Vietnam

With a site accessible only via narrow pedestrian alleyways, the studio looked to treat these constraints not as limitations but as "opportunities for social and spatial richness", it said.

Informed by Hanoi's urban alleyways, ODDO Architects created a stacked series of flexible spaces overlooking tall central voids, with the whole organised around a branched steel support painted bright red.

TH+ House references urban alleyways

"In Hanoi's alley neighbourhoods, vibrant community life is shaped by daily interactions – shared tea, small businesses, street games, and spontaneous social exchanges," said the studio.

"This social intensity became a key premise for the design of TH+ House," it continued. "Rather than stacking isolated rooms, the layout is conceived as a series of layered environments with varying degrees of privacy, allowing visual connections across floors."

The extension is organised around a red-steel support

On the ground floor, a new kitchen space, which sits alongside a bathroom and small courtyard, flows directly into a dining area within the footprint of the existing home. A wall of folding glass doors opens onto the adjacent alley.

Above, a living room, tea room and new bedrooms are kept visually linked through the introduction of internal windows and a bean-shaped opening, creating connections between both the new spaces and back into the existing home.

Perforated walkways help light filter through the extension

Each level connects back into the original TH House via perforated white-steel walkways, which enable natural light to filter through the interior. Exposed concrete floor plates and the central red-painted steel column support these walkways.

"The central red steel column acts as both the structural backbone and the spatial organiser of the house," the studio told Dezeen.

"By concentrating the load into a single element, it frees the plan from structural constraints, allowing for larger openings, flexible layouts, and continuous visual connections across the narrow footprint," added ODDO Architects.

"As a result, the column is not only a technical solution but also expresses the project's idea of openness, adaptability, and spatial generosity within tight urban conditions," it added.

Concrete is left exposed throughout

While the lower spaces are defined by dark stone floors and exposed concrete ceilings, the upper levels have been lined in timber panels to create a warmer character.

ODDO Architects has offices in Hanoi and in Havirov, Czech Republic, and is led by three partners: Nguyễn Đức Trung, Mai Lan Chi Obtulovičová and Marek Obtulovič. In 2021, it won emerging architecture studio of the year in the Dezeen Awards.

Previous homes by the studio include CH House, a dwelling on a similarly skinny site in Hanoi that is fronted by a breezy wall of perforated concrete blocks.

The photography is by Hoang Le.