R309.2 Separation required. ¹   Garages attached side by side to residences shall be separated from the residence and its attic area by means of a minimum 5/8-inch type X gypsum board applied to the garage side. Garages beneath habitable rooms, closets, bathrooms, toilet rooms, halls or utility spaces in residences shall be separated from adjacent interior spaces by a minimum 5/8-inch type X gypsum board applied to the garage side of all walls, ceilings and combustible structural supports. Gypsum board joints shall be finished in accordance with the manufacturer’s requirements.

Exception: Wood structural members of the minimum dimensions specified in Section 602.4 of the 2003 International Building Code for Type IV construction shall be acceptable without further protection.