A properly designed fire alarm system isn’t just about compliance, it’s about seconds. When smoke fills a hallway, those extra moments of early detection can mean the difference between a controlled evacuation and a tragedy. Yet most homeowners treat fire alarms like an afterthought, slapping up a couple of battery-powered units wherever they happen to have a stepladder handy. Whether you’re building new construction, upgrading an outdated system, or finally addressing those chirping detectors you’ve been ignoring, understanding the fundamentals of fire alarm system design will help you create a network that actually works when it matters most. Key Takeaways Fire alarm system design requires strategic detector placement in bedrooms, hallways, and all levels to ensure early smoke detection that can mean the difference between safe evacuation and tragedy. Dual-sensor smoke detectors combining ionization and photoelectric technologies provide the broadest protection, while heat detectors prevent false alarms in kitchens, garages, and attics. Hardwired systems are the standard for new construction with reliable interconnection and battery backups, while quality wireless fire alarm systems offer faster installation for retrofits without wall demolition. Mounting detectors on ceilings 4-12 inches below the surface with proper spacing from HVAC vents, corners, and ceiling fans maximizes