Question: Does the ADA cover private apartment buildings?
Answer: Generally no. Title III (the section of the ADA that involves the private sector) covers places of public accommodation and commercial facilities. Under the ADA, private residence are neither places of public accommodation nor commercial facilities. Part of the reason is that the federal Fair Housing Act includes accessibility requirements for private (and public) multi-family housing. These requirements were issued just a few years before the ADA passed. If a private apartment building has a rental office, rents a meeting room to the public or sells membership to its pool or health club, those areas would be places of public accommodation with obligations under the ADA.