The Build Housing Affordably Act directs the Department of Housing and Urban Development to study how the Buy America requirements under federal law affect affordable housing development, focusing on material costs, compliance expenses, project delays, and incomplete projects. The bill requires HUD to complete this study and report findings to Congress within 90 days. Until 60 days after the report is submitted, affordable housing projects funded through major HUD programs such as public housing, rental assistance, HOME partnerships, and community development block grants are temporarily exempted from Buy America requirements. Additionally, the bill establishes a 90-day deadline for HUD to decide on waiver requests from these Buy America rules, with waivers automatically granted if the department fails to meet this timeline.