Heavy materials like stone, mortar and clay were abandoned as building elements, with simple wooden walls, floors and partitions becoming prevalent. Native species like cedar ("sugi") were popular as an interior finish because of its prominent grain, while pine ("matsu") and larch ("aka matsu") were common for structural uses. Brick roofing tiles and a type of cypress called "hinoki" were used for roofs. It was sometime during this period that the hidden roof, a uniquely Japanese solution to roof drainage problems, was adopted.