412.4.1 Requires a fire-resistance rating on exterior walls less than 30 feet from lot lines or a public way to have not less than a 2 hour rating. Any reference to perpendicular or parallel orientation is only appropriate when discussing Fire Separation Distance, as found in FBC - Building Chapter 2 definitions. The term "Fire Separation Distance" is not mentioned in section 412.4.1, nor is it a referenced defined term in Section 412.2. Therefore, ALL exterior walls located less than 30 feet from lot lines or a public way shall have a fire-resistance rating not less than 2 hours, to include walls that are not only parallel to the lot line, but also perpendicular to it for a distance of 30'.
