Infill housing refers to the development of vacant or under-used parcels of land in an urban space. In many cases, infill development occurs on vacant lots in medium- to high-density areas within cities. However, it could also occur as part of the redevelopment of garages, car parks, or as upzoning in the backyards of existing homes.
The possibility to develop infill housing depends on the zoning regulation of the city where the development is to take place. In London, for example, prospective infill housing must take into account a law requiring at least 18 meters (26 feet) between windows in buildings that overlook each other. (ft.com, 2019)
In New York City, infill housing is dependent upon different zoning codes. For example, in Predominantly Built-Up Area, certain restrictions on lot size and use regulations come into play. (up.codes, 2021)
Proponents of infill housing argue that it can be used effectively to counter urban sprawl and address affordable housing concerns within rapidly developing urban centers. Opponents say it only adds to urban congestion, exacerbating traffic problems and leading to an overall reduction of green spaces. (sdnews.com, 2021)
Either way, successful infill development should fit contextually into the neighborhood in which the development is proposed, and take into account factors like access to amenities, transportation, and the existing architecture.