Learn About Seattle Residential Code (SRC), Chapter 19:

The Seattle Residential Code (SRC), Chapter 19: Roof Assemblies, provides regulations specific to single-family homes, duplexes, and townhouses with up to three stories within the city limits. While it adopts the 2018 International Residential Code (IRC) as its foundation, it incorporates additional amendments specific to Seattle’s needs and considerations. Here’s a deeper dive into its key aspects:

General Requirements (R903):

• Roof Decks: All roof decks must be covered with approved roofing materials like shingles, tiles, or metal, securely fastened to the structure according to the specific code provisions and manufacturer’s instructions.
• Flashing: Flashing installations are crucial to prevent moisture intrusion at various critical points like wall and roof intersections, coping joints, and penetrations through the roof plane. The code outlines specific installation methods to ensure proper water drainage and prevent leaks.
• Compatibility (R904): All materials used in the roof assembly, from underlayment to shingles and flashing, must be compatible with each other and the overall structure. This ensures the long-term performance and integrity of the entire roof system.
• Product Identification (R904): Roof covering materials delivered for installation should be clearly labeled with the manufacturer’s identification marks and any required testing agency labels. This ensures compliance with relevant standards and helps verify the material’s quality and suitability for the project.

Additional Specifics:

While the SRC Chapter 19 adopts the IRC as a baseline, it includes some crucial Seattle-specific amendments:

• Roof Loads: The code might account for specific regional factors like wind and snow loads, potentially influencing roof design and material selection compared to the national code.
• Material Approvals: Certain roofing materials approved for use nationally might require additional local approvals to ensure their suitability for Seattle’s climate and building practices.
• Fire-resistance Ratings: Depending on the building’s location and use, the code might specify higher fire-resistance ratings for specific roof components compared to the national code.