Bangkok, Thailand — No poor man ever seemed less likely than Sangwal Un-Seni to have a house of his own.
For many of his 59 years he has driven a samlor (Bangkok's motorized version of the rickshaw), which is called a ''tuk tuk'' because of the noise it makes.
He has never earned more than $100 a month, but he and his wife brought up numerous children in the sort of one-room slum dwellings in which 1 million (20 percent) of Bangkok's population live.
''We dreamed of having our own house,'' Mr. Sangwal says, ''but it was always something for the next life - not this one.''
People like Sangwal can rarely get over the first barrier - a down payment of something like $2,000.
Today, however, the dream house is reality. It may seem a poor affair to Western eyes - two small rooms on the second floor and kitchen, bathroom, and living space at ground level on a piece of land 40 by 16 feet.
But the location is good: a suburb 11 miles from the city center and close to shops, schools, and public transport. There is enough land along the house for a few vegetables.
New private houses nearby cost $40,000 to $50,000. Sangwal is buying his much more modest home after putting down less than $200 and promising to contribute his own labor.
The government project is called ''building together.'' Social workers and city officials say it could be a model for low-cost housing in developing countries.
The key to the program is the home buyer's own labor. Sangwal and his family put in about 1,500 man-hours mixing concrete, driving foundations, laying building blocks, and even making some of the easily assembled components.
Experts were on hand to guide them, and the building site has its own workshop for components.
The family's work was valued at approximately $500 - around 121/2 percent of the cash price of their house. That sum is deducted from the purchase price, which Sangwal will pay off at $35 a month for the next 15 years.
The house has given the family another source of income. In the front verandah they have set up a small food shop that will make it easier to keep up payments on the house.
Some of their neighbors have been trained and encouraged to find extra income for the same reason.
A variety of cottage industries has developed as a result: People make clothes and toys, raise mushrooms, and produce a variety of handicrafts.
Even an English class has been formed because some knowledge of the language can mean a higher wage in Bangkok.
Soon there will be 150 families on the site. Trees and flowers are already covering the scars of development. There are a community center, playground, and child-care facilities, and plans for a health clinic.
Outside help as well as the will and work of the participants made it possible.
Money for building and house mortages was provided by the Thai government. The four-acre site was bought with money lent by a West German charity. The Dutch government provided money for all infrastructure - water supply, drainage, and so on.
Management and technical assistance came from the internationally funded Asian Institute of Technology.
Much of the success can be ascribed to the enthusiasm and energy of institute officials like Wiyada Tasakorn, who has been with the project since its inception.
''The most exciting and important thing has been to see people develop their own self-reliance,'' she says. ''We believe that bringing house ownership within reach of the poorest people in the city will relieve many serious social problems.''
''The self-help and the help from one family to another we have seen here have built the houses,'' Ms. Tasakorn adds. The project has ''also created a new sense of social responsibility, which is rare in the overcrowded cities of Asia.''