But, he says, it's a price worth paying to be able to live on a prized plot in downtown Ho Chi Minh City where he can readily find work.
He lives with six relatives in a closet-sized space bursting with clothing, toys, a fridge, a bunk bed, a rice cooker, papers, groceries, toilet paper and other household items.
That leaves little room for sleeping so he spends most nights outdoors on a cardboard-lined lounge chair, which can be tricky in bad weather.
"It's really hard during the rainy season to find a dry place. If I can't, I just sleep standing up the whole night," said the 49-year-old manual labourer who has lived in the one-room home since 1975.
The 'micro-house' dwellings are dotted throughout Vietnam's bustling southern hub, occupied by families clinging to tiny plots of land in a city developing at breakneck pace.
Tucked away in winding alleys, nestled under new condo developments or sandwiched between street food stalls and shops, they are easily missed by the unattentive passerby.
But Cong says his home in the vibrant District 3 neighbourhood could sell for as much as $22,000 thanks to rising land prices.
Even so, like many others living in micro-houses, he says he wouldn't swap his prime location for a few extra metres of space.
"We're used to this area. If we move elsewhere we can't do business," said Cong, whose sisters and niece make a living as vendors in the city centre.
'Rather die than move'
Many of the mini-homes sprung up as larger housing plots that were whittled down by new, wider roads and other developments in the city.
Some may have started out on rice paddies during the period of French rule and ended up as squatter land, said Mel Schenck, an American who is writing a book about modernist architecture in Ho Chi Minh City.
There is no data on how many micro-houses exist today, and Schenck says they may eventually disappear from the rapidly transforming city.
"There's constant change going on, and I think in the long term that's a good thing, so if some of these disappear then that's what happens," he told AFP, while acknowledging their "picturesque value".
Land disputes are routine in the city, with downtown dwellers accusing city officials of underpaying for plots that are then sold on to developers for hefty sums.
That worries Nguyen Van Truong, who lives with five relatives in his 6.7-square-metre plot underneath a luxury highrise condo.
The 62-year-old supports his family doing odd jobs in the area but doesn't earn enough to buy a larger house in a more affordable part of town. He lives in fear that the government could force him out.
"I don't think we'd get that much compensation because the house is too small. We don't know where to go," he said, hanging his clothes outside the small space packed with belongings.
"If given the choice... to move elsewhere or remain in this tiny house, I'll choose to stay. I'd rather die than be forced to leave this spot."
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