502.11 Horizontal additions. Horizontal additions shall meet the following requirements:

502.11 Horizontal additions. Horizontal additions shall meet the following requirements:

When the cumulative area of horizontal additions, excluding basement additions, exceeds 30 percent of the area of the original building or structure, excluding basements, and the additions are structurally interconnected to, or not separated to comply with ASCE 7-16 Section 12.12.3, the entire structure shall comply with Section 304.4.

For the purpose of this Section 502.11, the term “original building or structure” shall mean the building or structure as it existed on the force based trigger date per IEBC. The combined building or structure may be used for more restrictive occupancy classifications as determined in San Francisco B ui lding Code Chapter 3 only when the structure as a whole meets the requirements in this code for such occupancy.