Architecture studio ISA has built a slender housing complex in Philadelphia by making the most of a plot of land about the width of a parking spot.
XS House is a six-storey apartment building in the city's Chinatown neighbourhood, alongside a busy highway called Vine Street Expressway.

It is located on a narrow plot of land that measures 11 feet (3.3 metres) by 93 feet (28 metres) and was previously a discrete, disused site for parking cars.
ISA built the rectangular residential complex on the site to include seven apartment units inside, with varying layouts.

"The site's extremely narrow footprint was expanded with strategic use of bays, mezzanines, and bi-level upper units while maintaining a minimal single-stair core layout," said the local studio.
"The existing lot was so marginal and small it was barely noticeable as a development parcel," ISA added.
"Originally used for informal surface parking for two cars, the lot now provides seven apartments."

In the basement is a two-bedroom unit that spans the length of the building. On the two uppermost floors are two, two-storey units.

Both the ground-floor unit and the one above feature mezzanines designed to be bedrooms, and open-plan living and dining rooms on their main levels.

In addition to increasing the number of floors allowed for the building, ISA also optimised the possible width of the structure.
"Despite the tiny scale of the site, facade projections permitted by the city...