Explain fire or horizontal separation distances for exterior wall fire resistance ratings.
Learning Objective: The student shall be able to explain fire or horizontal separation distances for exterior wall fire resistance ratings. The terms fire or horizontal separation distances appeared in a table in last week’s Coffee Break Training.
These terms describe the minimum distance requirements from one building to another—or to a nearby property line or exposure—to minimize the likelihood of exposure fires and establish minimum fire resistance ratings for the exterior walls. NFPA 5000™, Building Construction and Safety Code® and International Building Code® (IBC) address these dimensions slightly differently.
The IBC measures from the building face to the “closest interior lot line or to the center line of a street, an alley or public way.” Both codes have a means to deal with “imaginary” property lines when there is more than one building on the same property and exposure protection must be addressed.
Horizontal separations are measured at a 90° (1.57 rad) angle to the face of a building. For additional information, refer to International Building Code®, Chapter 6, or NFPA 5000™, Building Construction and Safety Code®, Chapter 7. Always refer to footnotes and exceptions. These buildings pre-date modern separation requirements.