Semi-detached housing (often abbreviated to
semi in the UK, Canada and Australia, as in "three-bedroom semi", sharing a
party wall and usually in such a way that each house's layout is a mirror image of its twin. This style of housing, although built throughout the world, is commonly seen as particularly symbolic of the
suburbanisation of the
United Kingdom and
Ireland, or post-war homes in
Central Canada. In
New England, certain other parts of the United States, and most of Canada, this style is sometimes colloquially called a
duplex; elsewhere, however, "duplex" refers to a building split into two flats/apartments (one above the other). The style is usually referred to in the
mid-Atlantic (particularly
Philadelphia) as a
twin.