This strategy works in some cases, based on LEED-NC Interpretations #5585, #5696 and #10098, not all of which have been specifically evaluated for the LEED-EBOM rating system. Per the Interpretations, this strategy can only be pursued if the portion located outside the building is protected from weather (which generally takes the form of an awning, overhang, or the second story for most buildings). It appears that use of exterior systems is more likely to be approved if the building can’t comply with the ten-foot minimum due to physical limitations. If you do use exterior systems, be sure to develop an effective cleaning program for exterior mats or grates, which are exposed to more dirt and particulates than interior entryway systems. If you’re concerned about earning this credit using exterior entryway systems, it may be worth it to submit a project-specific CIR.