Granny Flat and Casita FAQ for Chula Vista

Yes. Casita, granny flat, in-law suite and backyard cottage are everyday names; the Chula Vista Municipal Code uses two terms. An ADU (CVMC 19.58.022) can be detached, attached or converted from a garage or other existing space. A JADU (CVMC 19.58.023) is 500 sq ft or less inside an existing or proposed house, with an efficiency kitchen. A spare room without a kitchen is just a room. The JADU and attached ADU page compares the two smaller types.

State law allows a single-family lot one converted ADU, one JADU and one new detached ADU. The City Council voted 4-1 in September 2024 against allowing two detached units. AB 956, signed September 29, 2026, overrides that from January 1, 2027: cities must approve two detached ADUs per single-family lot, and may limit each to 800 sq ft. Multifamily lots follow other counts, covered on the rules page.

An attached ADU can: up to 25 ft (or the zone limit, if lower) and two stories. A detached ADU tops out at 16 ft. Near a major transit stop (within half a mile) it can reach 18 ft, with 2 more feet allowed to match the house's roof pitch. That's tall enough for a loft in some designs but not a full second floor by right. The code does contemplate an ADU built over an accessory structure, with 4 ft side and rear setbacks. Details are on the detached ADU page.

Yes. The City Standard ADU Plans, drawn by SnapADU, come in 498, 748, 749, 999 and 1,199 sq ft versions with a flipped layout for each, 12 sets in total. Building one lowers the City permit fee from $4,963 to $3,951. The three smallest stay under the 750 sq ft impact fee line. You still need Title 24 and truss calcs and a site plan.

Often no. Lots a half-mile walk or less from public transit owe no ADU parking, and the City's code counts a bus stop as transit, not only the E Street, H Street and Palomar Street trolley stations. If you convert the garage, you don't have to replace those spaces. Where parking does apply, it's one space at most, and tandem on the driveway counts. The garage conversion page covers the rest.

Only by the new unit. Under Prop 13 the main house keeps its base-year value, and the ADU is assessed at its new-construction value when it's finished, which can trigger a supplemental bill. SnapADU reports assessments of roughly $130 to $165 per sq ft for new San Diego ADUs, usually below contract cost. The calculator models $150 per sq ft at about a 1.1% rate.

It might, so check before you settle on a size. Newer districts such as CFD 16M charge a flat amount per ADU, $50 a year at FY23/24 rates. Older Eastlake and Otay Ranch CFDs, including 07M, 12M and 13M, tax building or living square footage taken from permits, and their rate documents don't say how an ADU is treated. Ask the City's CFD administrator. Most of west Chula Vista has no Mello-Roos.

Only on units over 500 sq ft. Then you pay two districts: Chula Vista Elementary at $2.37 per sq ft (effective October 12, 2026) and Sweetwater Union High at $3.01 per sq ft (effective June 22, 2026), about $5.38 per sq ft together. A 600 sq ft unit owes roughly $3,200, while one at 500 sq ft owes nothing. The cost page shows how this adds up.

Impact fees begin. The City's October 2025 fee bulletin exempts every JADU and any ADU below 750 sq ft. From 750 sq ft up, the unit is charged part of the single-family fee, scaled by its square footage relative to the house's. On a 1,600 sq ft home, the calculator shows 760 sq ft costing about $23k more than 740 sq ft west of I-805, and about $33k more east of it.

Western Chula Vista is generally Sweetwater Authority and eastern Chula Vista is Otay Water District, but the boundary doesn't follow I-805 exactly, so read your water bill. A new meter under 1 inch carries the County Water Authority capacity charge of $6,683 in 2026 ($5,617 from 2027), plus the local agency's own meter and capacity fees, which neither publishes in a form we could verify. The SDCWA charge applies to a new or upsized meter, so a unit that stays on the existing meter generally shouldn't trigger it. Confirm with your agency.

Usually not. Most of Bonita is unincorporated, so San Diego County PDS issues the permit under Zoning Ordinance section 6156, with its own fees and six County ADU plans (600 to 1,200 sq ft). Some Bonita-Sunnyside land was annexed and is in the City, and a mailing address won't tell you which you have. A County Property Summary Report or your tax bill's rate area will. Lots on septic need a County-approved septic layout first. See the Bonita ADU page.

The City doesn't publish review times. SnapADU reports about four to five months of permitting in Chula Vista. The state deadline: completeness within 15 business days, then a decision within 60. HOA review, if you have one, runs on its own schedule. The process page walks through each stage.

Licensed general contractors and ADU specialists, many working countywide. This site passes requests to a licensed San Diego general contractor. Whoever you hire, check the license on the CSLB site and get a written, itemized bid. The Chula Vista ADU builder home page compares the four unit types.