The provisions of Section 1103 of IEBC are adopted by reference with the following modifications:
1. Revise the exception to Section 1103.1 to read:
"Exception: Buildings of Group R-5 occupancy where the existing building and the addition together comply with the conventional light frame construction methods of the Chicago Building Code."
2. Revise Section 1103.2 to read:
"1103.2 Lateral force-resisting system.
Where the addition is structurally independent of the existing building, existing lateral load-carrying structural elements shall be allowed to remain unaltered. Where the addition is not structurally independent of the existing building, the existing building and its addition acting together as a single structure shall meet the requirements of Sections 1609 and 1613 of the Chicago Building Code using full seismic forces.
Exceptions:
1. Buildings of Group R-5 occupancy where the existing building and the addition comply with the conventional light-frame construction methods of the Chicago Building Code.
2. Any existing lateral load-carrying structural element whose demand-capacity ratio with the addition considered is not more than 10 percent greater than its demand-capacity ratio with the addition ignored shall be allowed to remain unaltered. For purposes of calculating demand- capacity ratios, the demand shall consider applicable load combinations with design lateral loads or forces in accordance with Sections 1609 and 1613 of the Chicago Building Code. For purposes of this exception, comparisons of demand-capacity ratios and calculation of design lateral loads, forces and capacities shall account for the cumulative effects of additions and alterations since original construction."
3. Delete Section 1103.3.