For exterior walls with a fire separation distance greater than how many feet must be rated for exposure to fire from the inside?

In the context of building codes and fire safety, the fire separation distance is a critical factor that determines how exterior walls are constructed concerning fire resistance. For exterior walls with a fire separation distance greater than 10 feet, the walls must be rated for exposure to fire from the inside. This requirement is designed to mitigate the risk of fire spreading from one structure to another, especially in urban areas or neighborhoods where buildings are in close proximity.

The rationale behind the 10-foot requirement is based on various factors that include the potential fire exposure from adjacent structures and the overall fire safety strategy laid out in building codes. When the distance exceeds this threshold, the logic is that the fire risk from neighboring buildings diminishes enough that the internal fire resistance of the exterior wall needs to be adequate to handle potential internal ignition sources without being directly affected by external fires.

Thus, when designing or assessing buildings, understanding that exterior walls need to be rated for such internal exposures when the fire separation distance is greater than 10 feet is vital for ensuring compliance with safety regulations. This is why the correct answer is 10 feet, aligning with established fire safety guidelines.