The Definitive History of Roofs
The roof is a part of a building envelope which covers the uppermost part of a building or shelter, providing protection from the weather, both rain and snow and wind, sunlight and heat. The word “roof” comes from the Old English “hrof” which means roof, ceiling, top, heaven, sky and also the “highest point of something” from the Proto-Germanic “khrofam”, Dutch “roef” which means “deckhouse, cabin, coffin-lid, Middle High German “rof” meaning “penthouse” and Old Norse “hrof” meaning “boat shed”.
Throughout history roofs have been made from the locally available resources. Cavemen covered their structures with sod roofs covered with earth and plants, providing shelters which offered great insulation but were not vermin or waterproof. The first glazed roof tiles were used in China 5,000 years ago and flat earthenware roof tiles were being used in Greece and Babylon between 4,000 and 5,000 years ago. Variations of the Greek clay tiles were brought here to England as early as 100 BC but these were an expensive option and only affordable for the richest and most powerful landowners.
Around 735 AD thatched roofs began to be developed and used with wood shingles being introduced around 300 years later. These presented such a fire hazard that in the 12th Century, King John issued a law in London that citizens should replace their thatch and reed roof coverings with clay tiles in an effort to prevent fires spreading.
Industrial production of clay tiles, however, didn’t begin until the 19th Century and these were followed about a hundred years later by the first concrete roof tiles. As these became more popular in the early 1900s roof tile manufacturers began adding a pigment to the concrete so that the tiles would resemble clay roofing tiles. Asphalt also became available in the 19th Century and rapidly became a popular product for roofing as it was able to be mass-produced at a reasonable cost.
Green roofing systems began being developed in Germany in the early 1970s and they have become more popular in recent years as we strive to become more environment-friendly and reduce our carbon footprints. A green roof is actually a living roof as the roof of a building is covered with a growing medium and vegetation. The green roofing system usually includes additional layers such as a root barrier and drainage and irrigation systems. Green roofs absorb rainwater effectively and provide insulation while also creating a habitat for wildlife, mostly insects and birds.
Most of the changes in roofing materials have taken place over the last 200 years or so. People in general still use the most available materials in their region, such as wood and metal in southern parts of North America, slate in the northeast, wood in the Midwest and tiles in the southwestern areas of North America. Here in the UK, pitched roofs are usually covered in tiles while flat roofs are generally covered with a membrane.
We are currently seeing rapid technological advances in materials of all types and this, coupled with a trend in energy savings is likely to lead to more eco-friendly choices for roofing in the future.