Three code requirements that are sometimes overlooked in mechanical design are Safety Guardrails Near Roof Edge, Insulation Required on Hot Surfaces, and Sidewall Grille Blade Spacing. Each topic is derived from the author's own experiences found many times while performing property condition assessments or peer reviews of other designs in actual facilities. This column is intended to be used as a summary checklist or a quick reference guide for HVAC design professionals, to avoid repeating these oversights on future building projects.