This bill amends the Housing Act of 1949 to permit Housing Preservation Grants to be used for accessory dwelling units (ADUs) , which are self-contained dwelling units located on the same parcel as a single-family home. This expansion aims to increase housing availability by allowing grants to fund the construction or rehabilitation of these additional housing units. The legislation introduces specific financial caps and owner requirements for ADU assistance. Assistance for an ADU cannot exceed 50 percent of its total cost and is capped at $100,000, with adjustments for inflation. Owners receiving ADU grants must reside in either the main dwelling or an ADU, maintain ownership, and ensure leases are not less than six months. Furthermore, the owner's income must not exceed 150 percent of the area median income, though the residency and ownership requirements expire after five years or upon the owner's death. The bill also sets general conditions for single-family housing grants, limiting assistance to homes at least 25 years old and capping individual grants at $200,000. Grantees must allocate at least 75 percent of the assistance for grants. Finally, the legislation authorizes $200,000,000 in appropriations for this section and permits up to 20 percent of funds to be used for administrative costs, outlining specific eligible and ineligible expenses.