Westchester communities are increasingly looking for housing that responds to changing family needs, smaller households, and increasing housing costs. An accessory dwelling unit (ADU) is a smaller, independent residential dwelling unit located on the same lot as a stand-alone single-family home. ADUs go by many different names, including accessory apartments and in-law flats. ADUs can be converted portions of existing homes (internal ADUs), additions to new or existing homes (attached ADUs), or new stand-alone accessory structures (detached ADUs). ADUs have the potential to increase housing affordability (both for homeowners and tenants), create a wider range of housing options within the community, enable seniors to stay near family as they age, and facilitate better use of the existing infrastructure in established neighborhoods.

Certain Westchester municipalities have signaled support for ADUs in their plans and have adopted zoning regulations that permit ADUs in single family residential areas. In an effort to provide all Westchester municipalities with guidance on ADU zoning regulations, Westchester County has developed ADU Model Ordinance Provisions. The goal of these provisions is to facilitate the land-use approvals and construction of ADUs in the County. The ADU Model Ordinance Provisions were developed based upon analysis of the ADU codes from various municipalities in the County, as well as upon successful zoning trends throughout the U.S.

The ADU Model Ordinance Provisions suggest respecting the look and scale of single-dwelling development while offering environmentally friendly housing choices with less average space per person and smaller associated carbon footprints. Other elements include limiting the square footage of the ADU and restricting front facing entrances and outdoor fire stairs.

For further information, contact Leonard Gruenfeld at  or Bill Brady at