In this study, we focus on the building system of “Pencil houses” in Hanoi, Vietnam. Pencil houses are conventional houses: about five story reinforced concrete structure in urban narrow plot. Building pencil houses, households order a small worker team to build structural parts of pencil houses. These team, by themselves, can build large parts of houses including foundation, concrete forms, steel bars, casting concrete, laying brick walls, and plasters. We interviewed with ten these teams, two small construction companies, among others in Hanoi, and make clear the pencil house construction process, contracts system, and workers condition.