Editing Roof (section)

===Support===
{{main|Domestic roof construction}}
[[File:Linkopings stadsbibliotek roof2.jpg|thumb|The roof of a library in [[Sweden]]]]
[[File:Tak - Ystad-2022.jpg|thumb|Roofs in the central district of [[Ystad]] 2022]]
The supporting structure of a roof usually comprises beams that are long and of strong, fairly rigid material such as [[timber]], and since the mid-19th century, [[cast iron]] or [[steel]]. In countries that use [[bamboo]] extensively, the flexibility of the material causes a distinctive curving line to the roof, characteristic of [[Japanese architecture|Oriental architecture]].

Timber lends itself to a great variety of roof shapes. The timber structure can fulfil an aesthetic as well as practical function, when left exposed to view.

Stone [[Post and lintel|lintels]] have been used to support roofs since [[Prehistory|prehistoric times]], but cannot bridge large distances. The stone arch came into extensive use in the [[Ancient Rome|ancient Roman]] period and in variant forms could be used to span spaces up to {{convert|140|ft|m|abbr=on|round=5|order=flip}} across. The stone arch or [[Vault (architecture)|vault]], with or without ribs, dominated the roof structures of major architectural works for about 2,000 years, only giving way to iron beams with the [[Industrial Revolution]] and the designing of such buildings as [[Joseph Paxton|Paxton]]'s [[The Crystal Palace|Crystal Palace]], completed 1851.

With continual improvements in [[steel girder]]s, these became the major structural support for large roofs, and eventually for ordinary houses as well. Another form of [[girder]] is the [[reinforced concrete]] beam, in which metal rods are encased in concrete, giving it greater strength under [[Tension (physics)|tension]].

Roof support can also serve as living spaces as can be seen in roof decking. Roof decking are spaces within the roof structure that is converted into a room of some sort.