Udomsak Sakrat, 29, was seen setting his room alight. By 12.30am Tuesday, the fire had engulfed the entire makeshift house he shared with other workers.
Workers living in 10 other domiciles at the construction site of a housing estate in Moo 3 village in Tambon Pawong managed to stop the blaze from spreading.
Prapas Khamsuwan, 42, a foreman at the site, said his nine-year-old son saw Udomsak lighting the fire.
Police arrived to place him under arrest.