Webinar: 2024 IECC Residential: Duct Systems & Duct Testing—What Changed and How to Comply

Join us for an in-depth look at the 2024 IECC residential duct system requirements. This session breaks down the latest code changes—covering duct location, insulation, leakage testing thresholds, and new documentation standards. We’ll walk through Section R403.3 step by step, highlighting the most significant updates, exceptions, and testing protocols.

A major addition in 2024 is a new performance-based table for total duct system leakage, replacing the old one-size-fits-all limit. The allowable leakage rate now varies by conditioned floor area served and the number of ducted returns—a fundamental shift that rewards tighter, more efficient duct design and installation.

Topics of Discussion:

• Testing Clarity Matters:
  The 2024 IECC clarifies that Total Duct Leakage (TDL), not leakage to outside, is the prescriptive compliance metric—ending years of confusion between testing types and helping ensure consistent enforcement across jurisdictions.
• New Testing Allowances:
  The new R403.3.8 table rewards well-designed, compact duct layout and penalizes oversized, leaky systems. Accuracy in test setup and documentation now matters more than ever.
• “Inside Conditioned Space” Isn’t Always What It Seems:
  Many systems labeled “inside” still fail compliance because of unsealed chases or ducts crossing unconditioned zones. The new ≤10-foot exception limit forces design and inspection teams to verify true envelope continuity.