Grandfamily Housing Act of 2021 This bill establishes grants through the Department of Housing and Urban Development for owners of intergenerational dwellings. Grants must be used to (1) provide services such as tutoring, health care services, and after-school care; (2) perform outreach to intergenerational families in the surrounding community; and (3) maintain spaces within the property to be used for programs and services for intergenerational families.