Looking at Buildings

, printed from the Looking at Buildings website on Sunday 22nd September 2019

Iron and Steel in Construction

Wrought ironGlossary Term [1] nails, hinges and other necessary components were the most common forms but lead and copper were also used for roof coverings. More skilled use of wrought ironGlossary Term [2] was made in the provision of decorative elements of buildings but the strutural use of iron only began in the late 18th century with Abraham Darby's Iron Bridge made entirely of iron arches and ribs cast in a foundry and transported to the building site for assembly. Although this advertised iron's remarkable architectural capabilities few architects designed buildings constructed entirely of this material. Transporting and erecting large cast ironGlossary Term [3] sections was both expensive and labourious.

Smaller items, such as solid or hollow iron columns, did find widespread application from the 1770s onwards. Their use reduced the need for heavy load-bearing internal walls or masonry piers and could be assembled quickly by unskilled labour. However, even when it was used it was common for the iron work to be concealed by other, traditional materials.

In textile mills of the early 19th century the use of iron beams and columns made it possible to increase the useful floor area. Although the exterior walls of the building were constructed in brick or stone masonry, the use of non-combustible iron in the interior also reduced the threat of fire, making it popular for a wide variety of new builings in the 19th century.

Otherwise iron continued to be employed on a grand scale only for major structures such as bridges. But the limitations of cast ironGlossary Term [4] meant that it was essential to use wrought ironGlossary Term [5] in such instances.

The use of wrought ironGlossary Term [6] trusses in combination with cast ironGlossary Term [7] columns led to the creation of the first large scale iron buildings without supporting masonry. This began in the second quarter of the 19th century with the use of standardised cast ironGlossary Term [8] beams with wrought ironGlossary Term [9] trusses in the construction of the Crystal Palace, 1851. The trusses made it possible to replace masonry arches and vaulting between the vertical supports and create buildings with wider spans and large internal spaces. This technology was widely applied to a variety of buildings from conservatories to exhibition halls and railway stations.

Steel can be rolled into shapes, such as railway tracks, but it is far less brittle than iron and could improve upon its predecessors. Independent steel-frame buildings were pioneered in the United States in the 1880s but the technology did not appear in Britain until 1906 at the Ritz Hotel.Even then the possibilities were not fully explored. The steel frame had a profound impact on the exterior appearance of buildings, which no longer relied on load-bearing masonry. The steel "skeleton" could simply be clad in a variety of other materials, principally glass. Steel trusses also allowed the construction of buildings with mighty internal spans.

Last updated: Monday, 26th January 2009