Buildings with a fire separation distance of 10 feet or greater require their exterior walls to be rated against what?

The correct answer highlights that buildings with a fire separation distance of 10 feet or greater must have their exterior walls rated against inside fire exposure. This requirement is based on building code regulations aimed at ensuring safety and reducing fire risks. While the exterior wall's fire rating considers fire exposure from both inside and outside, the primary focus when considering buildings with sufficient separation distance is to provide protection from potential fires that originate from within neighboring structures.

In this context, since the distance is considerable enough (10 feet or more), the building's exterior walls serve as a means of shielding against fires that could spread from adjacent buildings or structures. The most pressing concern in this scenario is to ensure that if a fire occurs inside a neighboring building, the rated exterior walls can withstand the heat and flames, thus preventing fire spread into the subject building.

The other options do not align with the specific requirements for buildings with this level of fire separation. For instance, walls do not generally need to be rated for outside fire exposure when they are adequately distanced from potential sources of fire in adjacent properties. Therefore, understanding the focus on inside fire exposure is crucial when navigating fire safety codes and regulations for commercial buildings.