Fire Separation

Fire separation walls contain fire spread between attached dwelling units or between houses and attached garages. These assemblies must achieve specific fire ratings (typically 1-hour or 2-hour) through combinations of materials and construction methods. Common fire separation uses 5/8-inch Type X fire-rated drywall on both sides of walls, proper sealing of penetrations, and fire-rated doors. The goal is containing fire long enough for occupant escape and fire department response.

Why It Matters

Fire separation saves lives by preventing rapid fire spread. In Denver, fire separation is required between: attached garages and living spaces, townhome units sharing walls, and basement apartments within single-family homes. Garage fire separation prevents vehicle fires from quickly spreading into homes—garage fires are common and dangerous. Proper fire separation includes sealing all penetrations (pipes, wires, ducts) with fire-rated materials, maintaining drywall continuity, and using self-closing fire doors.

Fire Separation Requirements

• Garage-to-house wall: 1-hour fire rating with 5/8-inch Type X drywall
• Garage ceiling (below living space): 5/8-inch Type X drywall
• Doors from garage to house: 20-minute fire-rated, self-closing
• Townhome party walls: 2-hour fire rating, sealed from foundation to roof
• Penetration sealing: Fire-rated caulk or foam at all pipe/wire penetrations
• Duct dampers: Fire dampers required in ducts passing through fire walls