The 2021 International Residential Code (IRC) is a comprehensive guide to building one- and two-family dwellings and townhouses up to three stories. It covers all aspects of construction, from foundations and framing to plumbing, electrical systems, and energy efficiency. Here's a summary of some key points:

Scope and Coverage:

• Governs construction of single-family homes, detached duplexes, and townhouses up to three stories.
• Excludes multi-family dwellings, commercial buildings, and industrial structures.

Key Updates in 2021:

• Enhanced Structural Requirements:
  • Braced wall lines must be securely anchored to physical walls.
  • Two-family dwellings require 1-hour fire separation regardless of lot lines.
  • Storm shelters need certified engineering designs.
  • Cripple wall requirements are exclusive to exterior walls.
• New Construction Techniques:
  • Appendix on cob construction provides guidelines for this traditional earthen building method.
  • Appendix on 3D printed construction addresses safety and quality standards for this emerging technology.
• Improved Ventilation and Appliance Regulations:
  • Balanced ventilation systems can now utilize 30% less airflow.
  • Commercial gas cooking appliances are prohibited in residential settings.
  • Increased water test head pressure ensures proper drainage functionality.

Additional Key Provisions:

• Structural Integrity: Precise specifications for foundations, footings, framing, and exterior wall coverings.
• Habitable Space: Defines minimum dimensions and ceiling heights for comfortable living areas.
• Safe Egress: Specifies requirements for stairways, exits, and emergency escape openings.
• Fire and Carbon Monoxide Safety: Mandates smoke alarms and carbon monoxide detectors for early warning.
• Mechanical Systems: Defines placement and safety regulations for HVAC systems and appliances.
• Plumbing, Electrical, and Fuel Gas: Ensures adherence to stringent safety and performance standards.