ADA (Americans with Disabilities Act) is a federal civil rights law that mandates specific accessibility standards in commercial buildings and certain multi-family housing — it does not apply to single-family residential construction. ANSI A117.1 is the technical dimensional standard (36″ doorways, 60″ turning radius, 250-lb grab bar load, max 1/2″ threshold) that ADA references and that residential designers use as a best-practice reference. Universal Design is a design philosophy producing spaces that work for everyone without appearing institutional — the framework for residential aging-in-place design. Visitability is a minimum standard: one no-step entrance, 32-inch minimum doorways, and a bathroom on the entry level. RainFire Builders targets Universal Design using ANSI A117.1 as the technical dimensional reference.