Effective waterproofing of complex roof details—including pipe boots, HVAC curbs, scuppers, parapet walls, and expansion joints—is critical to the long-term performance of low-slope and flat roofing systems. This guide addresses the unique challenges of waterproofing complex roof details using liquid-applied membranes, covering substrate preparation, application sequencing, quality assurance, and procurement considerations for roofing contractors, design consultants, and project managers.