per 2009 IBC, section 3104.5
"Exception: The walls separating the pedestrian walkway from a connected building and the openings within the 10- foot (3048 mm) horizontal extension of the protected walls beyond the walkway are not required to have a fire-resistance rating by this section where any of the following conditions exist:
exception 3, Buildings are on the same lot in accordance with Section 503.1.2."
so i can read this exception two different ways. first, walls are not rated if they are on the same lot. or second, if the building can meet the area limitations of the code, they can be considered as one building, and therefore no fire separation is required.
the first doesn't make sense, as the whole idea is to create a separation. but the second doesn't make sense either, because if one considers this as one building, then the pedestrian walkway is considered as part of the building.