Aging-in-place design allows people to live safely in their own homes as mobility, vision, and strength change with age. AARP reports that approximately 90% of adults over 65 prefer to stay home rather than move to assisted living. The features that make a home work at 80 — zero-step entries, wider doorways, curbless showers, grab bar blocking, lever hardware, enhanced lighting — also make it better at every age: easier with strollers and injuries, more welcoming to visitors with mobility limitations, more marketable to a broader buyer pool. The cost to incorporate these features during construction is 1–3% of the construction cost. The same features as a retrofit after completion cost 10–20× more — at a time when the homeowner is least able to manage a renovation project.