The client, the main catering supplier for Turkish Airlines flights, requested a seismic retrofit for their production and headquarters building in Istanbul. The building, consisting of six reinforced concrete blocks built in the 1970s, did not comply with seismic requirements. The scope of services included a seismic performance evaluation, resulting in three alternative retrofitting proposals: (1) seismic base isolation at the basement level, (2) buckling restrained braces (BRBs), and (3) steel plate shear walls (SPSWs) added to various floors to provide additional stiffness and dissipate energy through damping. Construction cost, applicable schedule, and business interruption durations were determined for each alternative, in addition to post-earthquake performance in terms of business sustainability. Services also included providing a site-specific Seismic Hazard Analysis (SHA) report, retrofitting design against punching risk by replacing steel brackets at the top of the columns, as well as preparing tender documents, assisting in contractor selection, and providing project and construction management at the site.