Back-to-backs are a form of terraced houses in the United Kingdom, built from the late 18th century through to the early 20th century in various forms. Many thousands of these dwellings were built during the Industrial Revolution for the rapidly increasing population of expanding factory towns. Back-to-backs share party walls on two or three of their four sides, with the front wall having the only door and windows.
As back-to-backs were built as the cheapest possible housing for the impoverished working class, their construction was usually sub-standard. Their configuration did not allow for sufficient ventilation or sanitation. Toilets and water supplies were shared with multiple households in enclosed courtyards. Back-to-backs gained an unfavourable reputation for poor levels of health and hygiene.
Around the mid-19th century, this form of housing was deemed unsatisfactory and a hazard to health. The passage of the Public Health Act 1875 (38 & 39 Vict. c. 55) permitted municipal corporations to ban new back-to-backs, replaced in the next phase of building by byelaw terraced houses. Leeds City Council opted not to enforce the ban, however; the popularity of back-to-back houses with builders and residents led to their continued construction in Leeds until the 1930s.
Most back-to-backs were demolished in waves of slum clearances, although many remain in Leeds and Bradford. The cities of Birmingham and Liverpool, where thousands of back-to-backs were built, both chose to retain a single example as a tourist attraction. The Birmingham Back to Backs are now operated as a historic house museum by the National Trust; other museum examples of back-to-back houses are managed by the Museum of Liverpool and Bradford Industrial Museum.