Inside El Cajon's city limits, the Building and Fire Safety Division permits ADUs, remodels, additions and new houses alike, and every application runs through the City's PACO portal, where Building quotes three to four weeks for a typical plan check. The ADU code was rewritten in May 2024 and amended three times since, last in February 2026 for the junior ADU occupancy rule, so it is closer to state law than most. Two points the state's housing department flagged in February 2025 are still in it, and the statute wins on both: a small house does not cap the ADU's size, and an attached ADU may rise to 25 feet or the zone's height. The City offers three free standard plans, a studio, a one-bedroom and a two-bedroom, and the 2025 fire map puts very high zones along parts of the city's edge.
Building in El Cajon with BHI
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BHI Builders takes on ADUs, remodels, additions and custom homes in El Cajon, whose ADU code was amended as recently as February 2026 and whose three free standard plans run from a studio to a two-bedroom. The page is built from El Cajon's code, its Council records and the state law above them.
Who issues permits here, and how does plan check run?
The City of El Cajon issues building permits through its Project Assistance Center, where Planning, Building and Fire Safety, Housing and Engineering sit together, and every project goes in through PACO, the City's online portal. You apply and upload plans, the City invoices the first review fees within one or two business days, review starts once they are paid, and corrections and approvals come back through PACO. Inspections are requested there too, and the City posts each day's inspection times and results.
The Building Division says a typical plan check takes about three to four weeks and a recheck one to two; fire plan check, by Heartland Fire & Rescue, takes about three weeks. No City page states the state's clocks, which still apply: a completeness answer within 15 business days and a decision within 60 days of a complete application. A plan review with no permit issued after a year expires under the City's 2025 building code amendments.
For the projects homeowners bring most often:
- An ADU or junior ADU: one building permit through PACO, a small Planning review fee, no City impact fee up to 750 square feet and no regional traffic fee at any size, from your own design or one of the three standard plans.
- Kitchen and bath work that relocates walls, pipes or circuits: a valuation-based building permit with its plan check charged as a share, under the 2025 codes in force since January 2026.
- An addition or a second story: the zone's height, 35 feet in the single-family zones, its lot coverage, the City's single-family design rules on eaves and windows, and school fees above 500 square feet.
- A new house: full plans, the hillside overlay's grading limits where it is mapped, the interface code in a very high fire zone, and a water meter from Helix or Padre Dam by where the lot sits.
Where do El Cajon's ADU rules differ from state law?
El Cajon's ADU and junior ADU rules are Municipal Code 17.140.180. Ordinance 5142 rewrote the section on May 28, 2024 and let a movable tiny home count as an ADU; Ordinance 5148 of January 28, 2025 allowed up to eight detached units on a lot with apartments and a path to legalize unpermitted units; Ordinance 5151 of May 13, 2025 answered most of HCD's February 2025 findings; and Ordinance 5173, adopted February 10, 2026 and in force 30 days later, took the junior ADU owner rule to the 2025 statute. The City has no ADU web page or handout, so the code is the only City statement of the rules.
HCD's letter of February 6, 2025 named ten points. Ordinance 5151 fixed the statute numbering, the new-house parking exception, the sprinkler rule and the attached garage as part of a house for a junior ADU, but two findings remain in the text, and the table states the statute there.
| Rule | In the City of El Cajon |
|---|---|
| Where | Any lot in a residential zone that allows a house or apartments, by right; planned residential developments follow their own chapter. |
| Units on a single-family lot | The code allows every combination the statute's mandatory units allow, though one line still reads one ADU and one junior ADU; the statute governs, so a converted unit, a new detached unit and a junior ADU may share the lot. |
| Apartment lots | Unused space in the building turned into one unit or more, up to 25 percent of its homes; two detached units with a proposed building, and with an existing one up to eight or as many as there are homes on the lot, whichever is fewer. |
| Size | Up to 1,200 square feet of living space; a junior ADU 500. The code adds that no ADU may be larger than the house, garages counted; HCD found that unlawful where it blocks an 800 square foot unit or a mandatory unit, and the statute governs. |
| Height, detached | The zone's height inside the house's setback lines. Outside them, 20 feet with a 5-foot setback, 16 with 4 feet and 12 with 3 feet, or 18 feet near transit or beside a house of two stories or more; all at or above the state's floor. |
| Height, attached | The code caps an attached unit outside the house's setback lines at 16 feet with a 4-foot setback and 12 with 3 feet. HCD found the cap applies regardless of setbacks under state law, which allows 25 feet or the zone's height, whichever is lower, up to two stories; the statute governs. |
| Setbacks | At least 3 feet from side and rear lines, outside the front and street-side setbacks unless that would block an 800 square foot unit; a conversion needs only enough room for fire safety. |
| Design | Similar materials, colors and style to the house, and the City's single-family rules on eaves and window area, for a unit outside the statute's mandatory routes; whether "similar style" is objective enough under state law is a question for Planning at intake. |
| Parking | One paved space per ADU, tandem or in the front setback allowed, except near public transit (half a mile), in a historic district, for a junior ADU or for a unit carved out of the house or an existing accessory building, near car share, where street permits are not offered, or with a new house; a garage lost to the unit is not replaced. |
| Sprinklers | None when the house has none, and an ADU with sprinklers does not require them in the house. The 2023 standard plans still print a line requiring sprinklers above 1,200 square feet, which cannot reach a unit capped at 1,200. |
| Movable tiny homes | Allowed as an ADU by administrative permit, 150 to 430 square feet, behind the house and certified to the RV standard; not in a very high fire zone unless the fire marshal agrees. |
| Junior ADU | Up to 500 square feet within the house, an attached garage included, with its own entrance, an efficiency kitchen and a recorded notice; the owner lives on site only when the bathroom is shared, as state law has said since January 2026. |
| Rentals | The code sets no term for an ADU and "not less than 30 days" for a junior ADU; state law requires more than 30 days for the mandatory units and junior ADUs, so 31 days is the floor there. A unit built with the City's ADU loan stays affordable for at least five years. |
| Selling a unit on its own | Never for a junior ADU; for an ADU, only through the qualified nonprofit route in state law, since the City has no condominium ordinance. |
| Legalizing an old unit | An ADU or junior ADU built without a permit may be legalized under the state's amnesty section. |
Where the City's code still reads differently from the statute, and what governs:
- The house-size cap, the attached height cap and the one-plus-one wording: the statute, as the table says. No HCD reply to the 2025 and 2026 ordinances was found.
- Impact fees: the code exempts a unit "less than 750 square feet"; the statute exempts 750 or less for an ADU and 500 or less for a junior ADU, and governs.
- The junior ADU's rental floor: the code's "not less than 30 days" against the statute's "longer than 30 days"; the statute governs.
- Parking near transit: the code's half mile, measured without the statute's walking distance, is more lenient, and the code governs.
Can you build from a pre-approved ADU plan here?
Yes. The City's Standard Plans are three free detached sets: a 560 square foot studio, a 649 square foot one-bedroom and an 802 square foot two-bedroom, each with the notes, erosion control, floor plan, utility plan, elevations, sections, details and energy forms, leaving the owner to add the site plan. The sheets are dated September 2023, the file was posted in January 2024, and the user agrees to release the City by using them. No City page links the file; ask Planning for it.
Two things to confirm at intake: the sets are drawn to the 2022 codes, and nothing says they were updated for the 2025 codes the City adopted in October 2025, which decides whether the state's 30-day review applies to them; and no City page offers designers outside City Hall a route to pre-approval, a program every California city owed by January 2025.
Fire zones, the hillside overlay, floods and historic homes
CAL FIRE released El Cajon's updated hazard map on March 24, 2025, and the City adopted it with the 2025 codes in Ordinance 5167 on October 28, 2025, replacing a map of 2015. Inside the city it shows very high zones in a pocket on the western edge by State Route 125, on the northeastern edge and along the eastern edge, a high area in the northwest and moderate fringes; most of the city is outside any zone. In the very high zones the City applies the 2025 Wildland-Urban Interface Code.
Where the hillside overlay is mapped, grading slopes may be no steeper than two to one or taller than 30 feet, the ground may not be raised or lowered more than 30 feet, and a civil engineer's grading plan and, in known hazard areas, a geotechnical report come with the application. The flood chapter governs work in the special flood hazard areas. A designated historic resource needs a certificate of modification for any addition or new building, with the Planning Commission sitting as the preservation commission, and an ADU in a historic district needs no parking.
A homeowners association may not forbid an ADU or junior ADU or restrict it unreasonably, under Civil Code 4751.
What does El Cajon charge, and what do the districts add?
The City's fee schedule adopted on May 12, 2026 and in force from July 13 charges a small Planning review fee for an ADU or junior ADU, lower for a state-exempt unit than for a new one, prices the building permit by valuation with plan check charged as a share of it, and adds a technology fee and a general plan surcharge. The City charges no impact fee on an ADU under its code, and its Council reports say it does not apply the regional traffic fee to ADUs or junior ADUs.
- Water. Helix Water District and Padre Dam Municipal Water District each serve part of El Cajon. Helix lets an added ADU share the house's meter, or upsize it, or take its own, the last two at its capacity fee and the County Water Authority's charge by meter size, and gives an ADU no separate fire line; Padre Dam's ADU rules were not found.
- Sewer. The City's own system, with a connection fee and an inspection fee set by resolution; no current amount for an ADU appears in the fee schedules, so ask Engineering. State law bars a connection fee on a unit inside existing space.
- School fees. Cajon Valley Union School District charges by the square foot of living area, its rate raised in July 2026, and Grossmont Union High its own; 500 square feet or less pays none in either.
How many ADUs El Cajon permits
El Cajon's ADU permits climbed every year in the state's data, from 10 in 2018 to 86 in 2025.
- 102018
- 182019
- 202020
- 322021
- 502022
- 682023
- 752024
- 862025
The ADU building permits El Cajon reported to HCD in each year's progress report (Table A2, ADU category), permitted rather than built, with junior ADUs inside the count because the form has no line for them. The 2020 report holds one unit from 2018 and one from 2019, and the 2023 report one from 1999. The City's own staff reports count 67 for 2023, 75 for 2024 and 86 for 2025, already past the 146 its Housing Element assumed for the whole 2021 to 2029 period; that element's own history for 2018 to 2020 reads differently from the state's figures.
Recent changes in El Cajon
What has changed in the City's permit rules since 2024, newest first.
El Cajon charges no impact fee on an ADU under its code and does not apply the regional traffic fee, so SB 1117 changes little at its counter, and school fees and Helix or Padre Dam capacity charges stay as they were. The wider picture is in our 2027 explainer.
The fiscal 2026-27 fee schedule took effect, adopted May 12, 2026, keeping the separate Planning fees for state-exempt and new ADUs.
Cajon Valley Union School District's new residential fee per square foot took effect.
The City's 2025 progress report counted 86 ADUs among 210 new homes permitted that year.
Ordinance 5173 was adopted, limiting the junior ADU owner rule to shared bathrooms and restating the ADU height rules; in force 30 days later.
Ordinance 5167 adopted the 2025 fire hazard map with the 2025 Building, Residential, Fire and Wildland-Urban Interface Codes, in force from January 2026.
The regional traffic fee rose for new homes; the City kept ADUs and junior ADUs out of it.
Ordinance 5151 was adopted in answer to HCD, fixing the numbering, parking, sprinkler and garage points but leaving the size and attached height caps.
The state's housing department found Ordinance 5142 out of step with state law on ten points.
Ordinance 5148 was adopted: up to eight detached ADUs on a lot with apartments, garages lost to an ADU not replaced, and unpermitted units open to legalization.
Ordinance 5142 rewrote the ADU section and let a movable tiny home count as an ADU.
The City's ADU loan program opened to owner-occupied lots, first come, first served.
How BHI approaches a El Cajon project
What we look at first on a El Cajon lot.
In El Cajon the first things we check are the two points the state's housing department flagged, the house-size cap and the attached height limit, and whether the lot lies in a very high fire zone at the city's edge or in the hillside overlay. Book a call to look at yours.
What an ADU might rent for in El Cajon
Nobody publishes rents for ADUs as their own class, so this uses HUD's FY2027 Small Area Fair Market Rent for El Cajon's central ZIP code, the figure the ROI calculator begins with: per bedroom count, the rent below which four in ten recent movers fell, utilities counted.
| ZIP | Studio | 1 bed | 2 bed | 3 bed |
|---|---|---|---|---|
| 92020 | $1,950 | $2,080 | $2,510 | $3,330 |
HUD's FY2027 rents for ZIP 92020 by bedroom count, as the ROI calculator carries them; the city's other two ZIP codes house more people on County land than in the city, so the calculator files them under the County. Try your own lot in the ROI calculator over 30 years.
Next steps
Set your lot against El Cajon's code, the HCD points and the fire map, price the unit, then open the pages that match your project.