The Affordable Housing Expansion Act seeks to expand access to affordable housing by amending federal prevailing wage determination requirements under subchapter IV of chapter 31 of title 40, United States Code. It updates the methodology for calculating prevailing wages, allowing the Secretary of Labor to use broader geographic groupings, such as metropolitan statistical areas, while preventing the use of metropolitan data for nonmetropolitan markets. The bill also mandates a review and revision of survey information collection methods to include reliable and objective data sources, potentially from Bureau of Labor Statistics surveys, and to ensure proportional representation of businesses in surveys. For projects under several Federal Housing Acts, the bill limits prevailing wage determinations to a single wage rate corresponding to the overall residential character of the project. Furthermore, it establishes the Davis-Bacon Modernization Working Group , comprising federal agency and industry stakeholders, to recommend updates and modernization of these wage requirements. This working group will explore applying residential classifications to taller affordable housing units, develop recommendations for waiving or streamlining prevailing wage rates for certain affordable rental projects, and review the feasibility of directing the Bureau of Labor Statistics to determine prevailing wages using existing data. The working group is required to submit a report with its findings and recommendations within one year of its establishment.