The installation of mechanical equipment on building rooftops requires the design of safe, efficient, and code-compliant structural platforms. This study focuses on the design and detailing of rooftop platforms in accordance with the provisions of the American Institute of Steel Construction (AISC). The platform is designed to support static and dynamic loads from mechanical units such as HVAC systems, including dead loads, live loads, wind loads, and vibration effects. The design methodology follows the guidelines of AISC 360 and AISC 303, ensuring structural safety, serviceability, and constructability using Load and Resistance Factor Design (LRFD) principles. Member selection, connection design, and stability checks are carried out with careful consideration of load transfer mechanisms, anchorage to the existing roof structure, and lateral bracing systems. Additionally, detailing aspects such as fabrication, erection, corrosion protection, drainage, and maintenance accessibility are addressed. Vibration isolation and fatigue considerations are also included to enhance durability. The outcome is a practical and efficient design framework that meets AISC standards while ensuring safety and economy in roof top platform construction.