Turf longhouses were homes built by Nordic people in Iceland in the 12th century. They were constructed from sod due to the lack of lumber in Iceland. Turf longhouses had warm interiors despite Iceland's cold climate because dirt is an excellent insulator. The layout included a main room divided into three aisles by support columns, with smaller side rooms and smoke holes at each end to vent fires built on dirt floors. While more flammable and less water resistant than other materials, turf was readily available for construction in Iceland.