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Revisiting Attached Garage Fire Separation

Many home inspector training manuals and continuing education courses address the fire separation requirements between an attached garage and living space. Specifically; fire rated drywall, self closing fire rated door, and ensuring the garage is 4 inches below the living space (although this may be waived for ADA compliance). I have seen some inspectors call out a wood door.  Also any pilot / flame in the garage should be 18” above the floor. However fire separation requirements have been revised and expanded. For instance in the IRC – R302.6 states in part that fire rated gypsum board shall not apply to garage walls that are perpendicular to the adjacent dwelling unit. Also, any openings from a garage directly into a room used for sleeping purposes are not permitted. Fire blocking is also required to eliminate concealed draft openings and to form a fire barrier between stories, and between a top story and the roof space. Fire blocking in wood framed construction should be in the following areas; in concealed stud spaces, vertically at the ceiling and floor, horizontally at intervals not exceeding 10 feet, at connections of soffits, dropped ceilings, and cove ceilings. So where should a home inspector be looking for fire separation:

  • Fire separation doors should be solid wood doors not less than 1 3/8” thick, solid or honeycomb core steel doors not less than 1 3/8” thick OR 20 minute fire rated doors
  • Enclosed accessible space under stairs shall have walls, under stair surface and soffits protected with ½” gypsum board
  • All doors should be equipped with a self closing device
  • Ducts in the garage penetrating the walls or ceilings separating the dwelling from the garage should be a minimum of No. 26 gauge steel, 1 inch minimum rigid nonmetallic or other approved fire rated material
  • No Duct openings are permitted in the garage
  • Any openings around vents, pipes ducts, cables, or wires shall be sealed with approved material to resist the passage of flame, smoke, and products of combustion
  • Wood Structural Panel floor structures shall be required to have a 5/8” gypsum wall board
  • Wood floor assemblies using dimensional lumber equal to or greater than 2 inch by 10 inch or any other approved floor assemblies demonstrating equivalent fire performance do NOT need 5/8” gypsum wallboard (basements only)
  • The annular space between the wall membrane and any electrical box shall not exceed 1/8”
  • Two family dwellings should be separated from each other by wall and floor assemblies having not less than a 1 hour fire rating
  • Two family dwellings equipped with an automatic sprinkler system should have a ½ hour wall and floor assembly separation

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