In buildings that have an elevator and four or more units, public and common areas must be accessible to persons with disabilities. This means that doors and hallways must be wide enough for wheel-chairs. Additionally, all units must have an accessible route into and through the unit, accessible light switches, electrical outlets, thermostats and other environmental controls, reinforced bathroom walls to allow later installation of grab bars, and kitchens and bathrooms that can be used by people in wheel-chairs. These requirements are federal minimum standards only and do not replace any more stringent standards in State or local law.