Prior ordinance history: Ord. No. 1945CCS.
Appendix Chapter A3 of the California Existing Building Code, 2025 Edition, entitled "Prescriptive Provisions for Seismic Strengthening Provisions of Cripple Walls and Sill Plate Anchorage of Light, Wood-Frame Residential Buildings" which adopts by reference Appendix Chapter A3 of the International Existing Building Code, 2024 Edition, as published by the California Building Standards Commission and the International Code Council (excluding Sections A301) is hereby adopted as the Voluntary Seismic Retrofit Requirements for Cripple Walls and Sill Plate Anchorage in Single-Family Dwellings of the City of Santa Monica.
(Added by Ord. No. 2537CCS § 4, adopted 3/28/17; amended by Ord. No. 2623CCS § 15, adopted 10/22/19; Ord. No. 2727CCS § 16, adopted 10/25/22; Ord. No. 2831CCS, 10/14/2025)
The provisions of this Chapter is intended to promote the safety and welfare of occupants in single-family dwellings by reducing the risks of earthquake-induced damage to existing wood-framed structures. The standards contained in this Chapter are intended to substantially improve the seismic performance of these buildings but will not necessarily prevent all earthquake-related damage. When fully followed, these standards will strengthen the portion of the structure that is most vulnerable to earthquake damage.
Prior to 1960, many wood-frame dwellings were built with raised wood floors supported by short wood stud walls known as cripple walls. These cripple walls are typically braced with weaker seismic materials such as portland cement plaster or horizontal wood siding. In addition, earlier building codes did not require wood-frame buildings to be bolted to their foundations. Recent earthquakes of moderate magnitude have shown that if a building has weak cripple walls or is unbolted, it may fall off its foundation. Fallen buildings have collapsed, caught fire or needed extensive repairs to restore their occupancy.
(Added by Ord. No. 2537CCS § 4, adopted 3/28/17; amended by Ord. No. 2831CCS, 10/14/2025)
Owners of any light wood-frame single-family dwellings, which contain one or more of the following structural weaknesses, are encouraged to seismically retrofit their buildings pursuant to the provisions of this Chapter:
(a) 
Sill plates or floor framing that are supported directly on the ground without an approved foundation system.
(b) 
Perimeter foundation system that is constructed only of wood posts supported on isolated pad footings.
(c) 
Perimeter foundation system that is not continuous at locations other than existing single-story exterior walls not exceeding ten feet (3,084 mm) in length forming an extension of floor area beyond the line of an existing continuous perimeter foundation or at porches, storage rooms and similar spaces not containing fuel-burning appliances.
(d) 
Perimeter foundation system that is constructed of unreinforced masonry.
(e) 
Sill plates that are not connected to the foundation or sill plate that are connected with less than what is required by the California Building Code.
(f) 
Floor framing members that are supported directly on an approved foundation system without a sill plate and are not connected to the foundation or are connected with less than what is required by the California Building Code.
(g) 
Cripple walls that are not braced in accordance with the requirements of this Chapter or cripple walls not braced with diagonal sheathing or wood structural panels in accordance with the California Building Code.
(h) 
Cripple walls or sill plates that are not connected to the floor diaphragm above or are connected with less than what is required by the California Building Code.
(Added by Ord. No. 2537CCS § 4, adopted 3/28/17; amended by Ord. No. 2831CCS, 10/14/2025)