According to the Department of Justice ADA Standards, “the Fair Housing Act requires that certain residential structures having four or more multi-family dwelling units, regardless of whether they are privately owned or federally assisted, include certain features of accessible and adaptable design according to guidelines established by the U.S. Department of Housing and Urban Development (HUD). These laws and the appropriate regulations should be consulted before proceeding with the design and construction of residential facilities.”
There are requirements for multi-family housing but not for most homeowners, as the ADA primarily refers to the accessibility of public facilities like parks, restaurants and hotels.