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ACCESSORY DWELLING UNIT CONVERSION Information Bulletin: Public – Building Code 2023-150

Department of Building and Safety
California State Government Code Section 65852.2 requires that local jurisdictions allow Accessory Dwelling Units (ADUs) by-right.
Section 65852.2(d)(2) prohibits the City from denying an application for a permit to create an ADU due to the correction of nonconforming zoning conditions, building code violations, or unpermitted structures that do not present a threat to public health and safety and are not affected by the construction of the accessory dwelling unit. The City is required to approve an application to convert unpermitted structures into an ADU where the resulting structure does not pose a threat to the public health and safety.
Unpermitted ADUs constructed prior to January 1, 2018, cannot be denied a permit provided the existing zoning violations do not present a threat to public health and safety. [Government Code Section 65852.23.]
The Department is responsible for deciding what poses a threat to public health and safety.
An existing accessory structure, whether permitted or unpermitted but existing prior to January 1, 2018, can be fully or partially demolished and a new ADU can be constructed in the same location and to the same dimensions as the existing structure; and is allowed to maintain the existing non-conforming setbacks.
This information Bulletin is intended to provide information on conversion of structures such as garages, utility rooms, storage rooms, recreation rooms, hobby shops, accessory living quarters, etc. to ADUs. It applies to permitted structures and to unpermitted structures existing prior to January 1, 2018.
I. GENERAL BUILDING CODE REQUIREMENTS
The following prescriptive requirements apply to one story structures. Any deviation from these prescriptive provisions or structures more than one story shall meet the requirements of the 2022 California Residential Code (CRC) and the California Building Code (CBC) as amended by the City of Los Angeles.
Note that each property may be subject to site-specific conditions and additional requirements may apply.
FOUNDATION
  1. Exterior walls and interior bearing walls shall be supported on continuous footings.
  2. Depth of footings below the natural and finished grades shall not be less than 12 inches, including footings underneath an infilled garage door opening or match existing footing depth if deeper than 12 inches. If any portion of the structure has an existing slab without any footing or is less than 12-inch in depth, the foundation shall be underpinned to a minimum of 12-inch in width and 12-inch in depth or match existing footing depth if deeper than 12 inches.
  3. Minimum concrete strength for new or underpinned footings shall be 2,500 psi.
  4. Existing footings are allowed to remain. New footings shall be reinforced with four½-inch diameter deformed reinforcing bars (two bars at top of footing, two bars at bottom of footing).
  5. An approved epoxy slab coating shall be applied on top of the slab if it does not have the required moisture barrier membrane. New concrete floor slabs on grade shall be placed on a 4-inch fill of coarse aggregate or on a 2-inch sand bed covered with a minimum 10 mil moisture barrier membrane.
  6. Existing slabs are allowed to remain. New concrete floor slabs shall be at least 3-½ inches thick and shall be reinforced with ½-inch diameter deformed reinforcing bars. Reinforcing bars shall be spaced at maximum 16 inches on center.
  7. Existing anchor bolts are allowed to remain. New anchor bolts shall be a minimum of ½-inch diameter x 10” long with 7” embedment spaced at a maximum 6 feet on center. Post-installed anchor bolts shall have an approved evaluation report and shall require special inspection by a deputy inspector.
  8. Existing sills and sleepers are allowed to remain. New sills and sleepers on a concrete slab which is in direct contact with the ground shall be preservative- treated wood in accordance with American Wood Protection Agency (AWPA) U1.
  9. Concrete foundation walls shall extend a minimum of 6 inches above the finished grade adjacent to the foundation.
  10. New exterior plaster (stucco) walls shall be provided with a corrosion resistant weep screed.
  11. Existing buildings located in a Methane Buffer Zone or a Methane Zone shall not be required to comply with LABC Chapter 71 Methane Mitigation, provided the existing slab remains undisturbed.
FRAMING
  1. Existing wall framing may remain unless there is an increase in load of over 400 pounds (i.e. mechanical equipment). If there are no ceiling joists, ceiling joists shall be required to accommodate additional loads (i.e. ceiling drywall, lighting, and mechanical equipment). New framing or altered framing shall comply with current LARC regulations.
  2. The infill walls of existing openings such as a garage door opening shall be 2×4 studs at a maximum 16 inches on center. Existing garage door headers are permitted to remain.
  3. Headers for new openings in existing walls shall comply with current LARC regulations.
  4. Bracing for new openings in existing walls shall comply with the following requirements. Walls with new openings shall provide a minimum total length of 10 feet of Wood Structural Panel (WSP) braced wall panels and shall meet End Condition A or B below. WSP braced wall panels shall be a minimum of 4 feet in length and shall have 15/32-inch minimum thickness with 8d common nails at 6 inch spacing along panel edges, 12 inch spacing at intermediate supports, and 3/8-inch distance to panel edge. ½-inch minimum thickness gypsum wall board shall be installed on the side of the wall opposite the bracing material.
END CONDITION A
END CONDITION B
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Return panel: 24” (does not count as bracing)
Distance D: 24”
MEANS OF EGRESS AND EMERGENCY ESCAPE
  1. The egress (main entry) door shall be side-hinged and shall be a minimum of 3 feet in width and 6 feet 8 inches in height. All interior doors through which occupants pass shall have a minimum width of 32 inches.
  2. Emergency escape openings shall be provided from every sleeping room and shall open directly to a yard or public way. Emergency escape openings shall have a minimum clear height of 24 inches, a minimum clear width of 20 inches, and a minimum openable area of 5 square feet. The bottom of the emergency escape opening shall not be greater than 44 inches above the finished floor.
FIRE PROTECTION AND FIRE-RESISTANCE RATED CONSTRUCTION
  1. Automatic fire sprinklers are required only if the main dwelling is required to be fully sprinklered. Automatic fire sprinkler system shall not be required for the ADU conversion when the existing house does not have an automatic residential fire sprinkler system.
  2. Exterior walls less than 5 feet from the property line of a non-sprinklered ADU conversion or less than 3 feet from the property line of a sprinklered ADU conversion shall be 1-hour fire-resistance rated construction. The 1-hour fire- resistance wall can be achieved by installing 5/8” type X gypsum board on the entire interior side of the wall up to the roof line.
  3. No openings shall be permitted in the exterior walls of a non-sprinklered ADU conversion where the exterior wall is less than 3 feet to the property line. The area of exterior wall openings of a non-sprinklered ADU conversion located between 3 feet and 5 feet of the property line shall be limited to 25% of the wall area.
  4. Carbon monoxide alarms shall be installed where the unit contains fuel burning appliance and shall be provided immediately outside of each separate sleeping area.
  5. Smoke alarms shall be provided in each sleeping room and immediately outside of each separate sleeping area. Smoke alarms or smoke detectors shall be installed a minimum of 20 feet horizontal distance from a permanently installed cooking appliance.

Exception:
Ionization smoke alarms with an alarm- silencing switch or photoelectric smoke alarms shall be permitted to be installed 10 feet or greater from a permanently installed cooking appliance.
Photoelectric smoke alarms shall be permitted to be installed greater than 6 feet from a permanently installed cooking appliance where the kitchen or cooking area and adjacent spaces have no clear interior partitions and the 10 foot distances would prohibit the placement of a smoke alarm or smoke detector required by other sections of the code. Smoke alarms listed for use in close proximity to a permanently installed cooking appliance
INTERIOR ENVIRONMENT
  1. Habitable room shall have a floor area of not less than 70 square feet and shall not be less than 7 feet in any horizontal dimension. A minimum ceiling height of 7 feet shall be provided throughout.
  2. The ADU shall provide permanent provisions for cooking, at a minimum: kitchen sink, cooktop, and refrigerator, each with 30 inches minimum clear space in front.
  3. Habitable rooms shall have natural ventilation through an opening of not less than 4 percent of the room’s floor area, unless a whole-house mechanical ventilation system is installed.
  4. Habitable rooms shall have natural lighting through an aggregate glazing (window) area of not less than 8 percent of the room’s floor area, unless an artificial lighting is installed to produce an average illumination of 6 foot-candles at a height of 30 inches above the floor in conjunction with a whole-house mechanical ventilation system.
  5. The unit shall provide heating facilities capable of maintaining a room temperature of not less than 68oF at a point 3 feet above the floor and 2 feet from exterior walls. Portable space heaters shall not be used to achieve compliance with this section. [The CF1R Residential Certificate of Compliance will dictate what means of heating will be provided.]
  6. The unit shall provide a separate bathroom containing a toilet, sink, and bathtub or shower. Bathrooms shall provide mechanical exhaust fans with a minimum intermittent ventilation rate of 50 cubic feet per minute. The center line of any toilet shall be located a minimum 15” from any side wall or obstruction, and a minimum 24” clear space in front of the toilet shall be provided.
  7. Attics shall provide a minimum cross ventilation of 1/150 of the area of the vented space. An attic access opening shall be provided with minimum dimensions of 22 inches by 30 inches and a minimum headroom clearance of 30 inches. The attic access opening shall be located in a hallway or other readily accessible location.
ENERGY / GREEN BUILDING / PLUMBING / ELECTRICAL CODES
  1. The ADU shall comply with California Building Energy Efficiency Standards (Title 24). The CF1R Residential Certificate of Compliance shall be attached to the plans. If the CF1R requires Home Energy Rating System (HERS) field verification, the CF1R shall be registered with a certified HERS provider.
  2. The ADU shall comply with applicable Los Angeles Green Building Code requirements. At a minimum, Green Building Code Forms GRN 1, GRN 11, GRN 14, and GRN 16 shall be attached to the plans.
  3. Detached ADUs are not required to have independent service utility (drainage) connections provided the existing service utility complies with the current plumbing code.
  4. The ADU shall have a separate water shut off valve, accessible in the unit.
  5. The ADU shall require a separate electrical panel.
II. SETBACKS
Existing permitted structures and unpermitted structures existing prior to January 1, 2018, can maintain their existing non-conforming setbacks provided the existing reduced setbacks do not present a threat to public health and safety.
III. PLAN CHECK REQUIREMENTS
PLAN REQUIREMENTS
Document submittal requirements are listed in Information Bulletin P/GI 2020-008.
RECORDS RESEARCH
If the existing building has previously been permitted, a copy of the building’s Certificate of Occupancy and previous building permits shall be provided at the plan check stage to verify the permitted use of the structure.
ACCEPTABLE EVIDENCE FOR ESTABLISHING THE CONSTRUCTION DATE OF UNPERMITTED ACCESSORY STRUCTURES
Documentation establishing that the unpermitted structure was built prior to January 1, 2018 shall include at least one of the following:
  1. Code Enforcement case documentation (i.e. Orders to Comply) .
  2. Rent Stabilization Ordinance (RSO) Rent Registration Certificate.
  3. Contractor’s bills and/or building material receipts.
  4. Utility bills pertaining to the unpermitted construction.
  5. A signed and dated lease agreement.
  6. Other third–party created documents acceptable to the Department.
IV. TYPICAL CLEARANCES
LOS ANGELES DEPARTMENT OF WATER AND POWER (LADWP)
Approval will be required if the existing structure is located in a Public Utility Easement or within 10’ of a Public Utility Easement. Additional information may be found at the following link: LADWP Encroachment Process.
LOS ANGELES DEPARTMENT OF PUBLIC WORKS, BUREAU OF ENGINEERING (BOE)
Approval is required from BOE for all ADUs to asses sewer capacity and availability (i.e. “sewer availability” clearance). Additionally, permit applications for unpermitted dwelling units or projects that alter the site’s existing drainage pattern require roof drainage clearance.
LOS ANGELES FIRE DEPARTMENT (LAFD)
Approval is required if any attached/detached ADU is more than 150 feet from the edge of the roadway or if any detached ADU is located in a designated Very High Fire Hazard Severity Zone (VHFHSZ).
V. INSPECTION REQUIREMENTS
The Department of Building and Safety, at the discretion of the field inspector, may require existing covered or concealed work to be exposed for examination during the inspection phase to verify appropriate installation.
VI. CERTIFICATE OF OCCUPANCY
Once all inspection requirements have been met and the permit has been finalized; and all required clearances from other city departments are obtained, a certificate of occupancy will be issued.
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