History of Roofing

The history of roofing follows the materials people could gather, make and transport. For most of human history roofs were made from whatever grew or lay nearby: branches, grass, reed, turf, bark and animal hides. Fired clay tiles, cut stone and sheet metal arrived later and spread with trade, empires and religions. Industrialisation then made factory products such as corrugated iron, rolled zinc, asphalt shingles and plastic membranes available almost everywhere.

Dates in roofing history are often uncertain. Organic roofs rot and rarely survive, so archaeologists usually infer them from post holes, collapsed debris or fallen tiles.

Timeline of key developments

• About 23,000 years ago: brushwood huts at Ohalo II on the Sea of Galilee, among the oldest known built shelters.
• About 2400-2200 BCE: pan and cover clay tiles at Qiaocun on the Chinese Loess Plateau, described by its excavators as the earliest known composite-tiled roofs.
• 7th century BCE: the interfitting Protocorinthian tile system on the Old Temple at Corinth, Greece.
• Roman period: flat tegula and curved imbrex tiles used across the empire; lead sheet used for watertight roofs.
• 588 CE: roof tiles reach Japan with Baekje craftsmen building Asuka-dera.
• 1212: new thatched roofs banned in London after a major fire.
• 1393-1401: the hammerbeam roof of Westminster Hall, the largest medieval timber roof in northern Europe.
• 1406-1420: the yellow glazed roofs of the Forbidden City, Beijing.
• 1666: the Great Fire of London leads to rebuilding rules favouring brick and stone.
• 1829: Henry Robinson Palmer patents corrugated metal sheets.
• 1898: Welsh slate output peaks at over 500,000 tons.
• 1900: Ludwig Hatschek patents his asbestos cement process (later sold as Eternit).
• 1903: asphalt shingles first cut from roll roofing in Grand Rapids, Michigan.
• 1960s-1970s: modern green roofs develop in Germany; modified bitumen develops in Europe.
• Early 1990s: TPO single-ply membranes introduced.
• 1998: the Cool Roof Rating Council is founded in the United States.

Recurring themes

Three forces shape most changes. Fire pushed cities to ban thatch and timber and to adopt tile, slate and metal. Transport decided which materials were affordable: canals and railways spread Welsh slate, and steamships carried prefabricated iron buildings to the colonies. Industrial chemistry produced asphalt, synthetic rubber and plastics in the 20th century, changing low-slope roofing completely. More recently, energy use and urban heat have driven interest in vegetated and reflective roofs.