Federal Oversight of Construction Use and Safety Act or FOCUS Act This bill requires the General Services Administration (GSA) to limit scope or size escalations for public building projects. GSA must also report to Congress on certain project scope and cost changes, public safety, and utilization of public buildings. Specifically, GSA must not allow the scope or size of a project to increase or decrease by more than 10% without congressional approval. GSA must report (1) when the estimated maximum cost increases by more than 5%, (2) when the scope or size of a project increases or decreases by more than 5%, (3) any safety incidents as a result of criminal or other activity impacting public safety in and around public buildings, and (4) public building utilization rates and locations of tenant agency activities near such buildings. GSA must notify Congress upon accomplishing certain milestones for all congressionally approved projects. GSA must also share space utilization information among federal agencies to coordinate consolidation and sharing of facilities. The bill also requires the Government Accountability Office to review and report on special use spaces (e.g., conference centers and fitness centers) in federal buildings to determine levels of utilization, opportunities for sharing, and other efficiencies.