ADU Builder in Sierra Madre, CA: Permits, Pre-Approved Plans and Costs

Pre-approved ADU plans through the Sierra Madre Planning and Community Preservation Department

The Sierra Madre Accessory Dwelling Units page lists the city's pre-approved ADU program using plans from two design firms. The current catalog includes the DomADU plan from Mei Li Homes LLC, a 400 square foot one bed one bath layout with a pitched roof, and the neXt 400 pre-approved ADU plan from neXt dwelling LLC, a 400 square foot studio layout available in several architectural styles and roof types. Using one of these plans is intended to expedite the plan check review time, but the property still has to meet Title 17 Chapter 17.22 of the Sierra Madre Municipal Code and the development rules for the underlying zone. Contact the Sierra Madre Planning and Community Preservation Department to confirm the current plan list and any designer coordination that the city requires for the chosen plan.

Sierra Madre permit process, Ordinance 1494, and the 60 day state clock

On May 26, 2026 the Sierra Madre City Council adopted Ordinance No. 1494, updating the Accessory Dwelling Unit Ordinance. Exhibit 1 of the ordinance amends Chapters 17.08 and 17.22 of Title 17 of the Sierra Madre Municipal Code, which is the chapter that governs all ADUs constructed in the city. The city's ADU review process starts with a completeness check in 15 business days, then compliance review by Planning, Building and Safety, and Fire within 60 days. California Government Code Section 66317(a)(3) gives the city 60 days to approve or deny a complete application when an existing single family home is on the lot, and Section 66317(a)(2)(A) requires the completeness decision within 15 business days. If the city does not act within 60 days, the application is deemed approved under state law, less any applicant requested delay. L Square prepares the submittal package, schedules the intake, and tracks both clocks so the project does not slip into the next planning cycle.

Size, height, and setback rules in Sierra Madre

The Sierra Madre ADU FAQ on the city's ADU page states the city shall allow an ADU of at least 800 square feet as the state-mandated floor, whether detached or attached, regardless of zoning requirements for lot coverage, floor area, and open space, and regardless of the size of the existing residence. The allowed size may be increased up to a maximum of 1,200 square feet if the lot coverage, floor area, and open space requirements can still be met. The minimum setback from a side or rear property line is 4 feet, the front setback is the same as required for a primary structure in the zone, and the maximum height is 16 feet unless the ADU is converted from an existing structure without modification or reconstruction. The state floor in Government Code Section 66321 does not apply; Section 66321(b)(2)(A) and (B) sets the 850 square foot studio or one bedroom detached ADU floor and 1,000 square foot multi bedroom detached ADU floor, and Sierra Madre cannot undercut that floor. Government Code Section 66314(d)(5) caps a detached ADU at 1,200 square feet, and Section 66314(d)(7) lets the city clear existing structures and same location rebuilds from the 4 foot setback ceiling.

Parking, JADU, AB 2533 legalization, and AB 449 protections for older Sierra Madre ADUs

The Sierra Madre ADU page lists Junior Accessory Dwelling Units capped at 500 square feet, with shared sanitation allowed, an efficiency kitchen in lieu of a full kitchen, and owner occupancy in either the primary home or the JADU subject to a recorded deed restriction before the permit issues. For older unpermitted units, the Sierra Madre Planning Division runs the state legalization path under Assembly Bill 2533 for any ADU or JADU constructed prior to January 1, 2020. Government Code Section 66314(d)(10) caps required parking at one space per bedroom or per unit, Section 66314(d)(11) bars the city from requiring replacement parking when a garage, carport, or covered parking structure is converted to an ADU, and Section 66322(a) lists six situations where parking may not be imposed, including ADUs within one half mile walking distance of public transit. Assembly Bill 449 adds hate crimes and civil rights protections that apply to all city processes, including ADU intake, and the city posts the notice on the ADU page.

Public Facilities Fees effective July 1, 2026 and state preemption on impact fees

Effective July 1, 2026 all Accessory Dwelling Unit applications received on or after that date may be imposed with Public Facilities Fees under City Council Resolution 26-50. The Notice of Changes posted by the Planning and Community Preservation Department shows seven fee categories including General Government, Library, Public Safety, Parks, Traffic, Water, and Sewer, with FY 2026-2027 base amounts of $3,883.74 General Government, $2,219.43 Public Safety, $2,998.02 Library, $20,050.98 Traffic, $7,853.67 Parks, and $2,388.68 Water, plus Sewer. ADUs with 750 square feet or less of interior livable space are exempt under Government Code Section 66311.5(c)(1), and impact fees above that floor are charged proportionately in relation to the primary dwelling square footage. Section 66311.5(b) treats an ADU as not a new residential use for water and sewer connection fees. The state's ADU approval article supersedes any conflicting local ordinance, so Sierra Madre cannot impose a stricter standard on size, parking, setbacks, or approval timelines than state law allows.

Cost ranges and what is included at L Square

L Square model prices for ADUs that meet the 1,200 square foot state ceiling start at $180,000 for the smallest prefab layout, with $240,000, $295,000, and $354,000 covering the larger 2 bedroom plans published on lscontractor.com/adu-cost-orange-county/. Those prices are the same for Los Angeles County cities including Sierra Madre, and they cover design, engineering, permits, and build for the published plan footprint. Site specific costs such as slope work, utility trenching, retaining walls, and code upgrades for Very High Fire Hazard Severity Zones are quoted after the lot review. Confirm the final number with the Sierra Madre Planning and Community Preservation Department for the Public Facilities Fee and any water meter fees effective July 1, 2026. L Square holds California Contractors State License Board number 1095476 and writes every proposal in writing before any work starts.

Official Sierra Madre ADU sources

• The Sierra Madre Accessory Dwelling Units page states that on May 26, 2026 the Sierra Madre City Council adopted Ordinance No. 1494, updating the Accessory Dwelling Unit Ordinance. Exhibit 1 of the ordinance amends Chapters 17.08 and 17.22 of Title 17 of the Sierra Madre Municipal Code, which is the chapter that governs all ADUs constructed in the city. Official source
• The Sierra Madre Planning and Community Preservation Department home page confirms the department's role over Planning and Zoning, Building and Safety, Code Enforcement, and Project Transparency, including the Accessory Dwelling Units, Urban Lot Split, and Sustainable Housing and Grant Programs listed in the left navigation. Official source
• The Sierra Madre Notice of Changes for Accessory Dwelling Units states effective July 1, 2026, Public Facilities Fees shall be imposed for permit applications received on or after that date under City Council Resolution 26-50. ADUs with 750 square feet or less of interior livable space are exempt. The notice lists seven fee categories: General Government, Library, Public Safety, Traffic, Water, and Sewer, with FY 2026-2027 base amounts including $3,883.74 General Government, $2,219.43 Public Safety, $2,998.02 Library, $20,050.98 Traffic, $7,853.67 Parks, and $2,388.68 Water. Official source
• California Government Code Section 66317(a)(3) gives the city 60 days to approve or deny a complete ADU application when an existing single family home is on the lot, and Section 66317(a)(2)(A) requires a completeness decision within 15 business days. Official source
• California Government Code Section 66314 limits a detached ADU on a lot with an existing or proposed primary dwelling to 1,200 square feet of floor area, and Section 66314(d)(7) lets the city clear existing structures and same location rebuilds from the 4 foot setback ceiling. Official source
• California Government Code Section 66311.5(c)(1) bars a local agency, special district, or water corporation from imposing any impact fee on an ADU with 750 square feet of interior livable space or less, and impact fees above that floor are charged proportionately in relation to the primary dwelling square footage. Official source