Ironwood shingles or sirap are one of the traditional roofing materials of Indonesia. Ironwood is known locally as Kayu Besi or Ulin. It is one of the world's most durable timbers.
Originating from Kalimantan (Borneo) they have been used for hundreds of years by the locals there for traditional housing. The Dutch colonials introduced them to the rest of the archipelago and they are now found on many large government buildings as well as high class houses.