Los Angeles Municipal Code Div. 8 Alterations – Level 2

(Title Amended by Ord. No. 188,797, Eff. 12/31/25.)

Section

91.2.800 Basic Provisions.

91.2.805 Structural.

(Amended by Ord. No. 188,797, Eff. 12/31/25.)

Chapter 8 of the CEBC is hereby adopted by reference except as amended herein.

(Added by Ord. No. 188,797, Eff. 12/31/25.)

Section 805 of the CEBC is hereby adopted by reference except as amended herein.

91.2.805.3. Existing structural elements resisting lateral loads. Except as permitted by CEBC Section 805.4, where the alteration increases design lateral loads, or where the alteration results in prohibited structural irregularity as defined in ASCE 7, or where the alteration decreases the capacity of any existing lateral load-carrying structural element, the lateral force-resisting system of the altered building or structure shall meet the requirements of Section 1609 of the California Building Code and Section 304.3.2 of this code. Reduced seismic forces, in accordance with CEBC Section 304.3.2, shall be permitted, provided the reduced seismic load is not less than the original building permitted seismic loads.

EXCEPTIONS:

1. Except for Unreinforced Masonry Buildings (URM), any existing lateral load-carrying structural element whose demand-capacity ratio with the alteration considered is not more than 10 percent greater than its demand-capacity ratio with the alteration ignored shall be permitted 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 Section 1609 of the California Building Code and Section 304.3.1 or 304.3.2 of this code. The same methodology shall be used for the altered and unaltered structures. 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. When calculating demand-capacity ratios for wind, the date of original construction shall be permitted to be taken as the date of completion of a prior addition, alteration or repair in compliance with Section 1609 of the California Building Code or the code wind forces in effect at the time. When calculating demand-capacity ratios for earthquake, the date of original construction shall be permitted to be taken as the date of completion of a prior addition, alteration or repair in compliance with CEBC Section 304.3.1 or CEBC Section 304.3.2, Item 1 or 3, or the full or reduced seismic forces in effect at the time. Reduced seismic loads, in accordance with CEBC Section 304.3.2, shall be permitted provided the reduced seismic load is not less than the original building permitted seismic loads.

The alternations do not create structural irregularity as defined in ASCE 7 or make an existing structural irregularity more severe.

2. For Unreinforced Masonry (URM) Buildings, any existing lateral load-carrying structural element whose demand-capacity ratio with the alteration considered is less than 10 percent greater than its demand-capacity ratio with the alteration ignored, must comply with CEBC Appendix Chapter A1. Any existing lateral load-carrying structural element whose demand-capacity ratio with the alteration considered is 10 percent or greater than its demand-capacity ratio with the alteration ignored, must comply with CEBC Section 304.3.1.

Structural analysis per CEBC Appendix Chapter A1 is required for any alterations to crosswalls or diaphragms.

3. Except for Unreinforced Masonry Buildings (URM), buildings in which the increase in the demand-capacity ratio is due entirely to the addition of rooftop-supported mechanical equipment individually having an operating weight less than 400 pounds (181.4 kg) and where the total additional weight of all rooftop equipment placed after initial construction of the building is less than 10 percent of the roof dead load. For purposes of this exception, “roof” shall mean the roof level above a particular story.

4. Except for Unreinforced Masonry Buildings (URM), increases in the demand-capacity ratio due to lateral loads from seismic forces need not be evaluated for the installation of rooftop photovoltaic panel systems where the additional roof dead load due to the system, including ballast where applicable, does not exceed 5 pounds per square foot (psf) (0.2394 kN/m 2 ) and does not exceed 10 percent of the dead load of the existing roof.