Everything homeowners need to know about building an accessory dwelling unit in Elk Grove, California - size limits, setbacks, permits, and the city's free pre-approved plans and over-the-counter program.
| ADU type | Max size | Max height | Notes |
|---|---|---|---|
| Detached, new construction | 1,200 sq ft | 16 ft generally; up to 18 ft (plus 2 ft for a matching roof pitch) within a half-mile of transit; up to 30 ft in agricultural/agricultural-residential zones | Minimum unit size is 150 sq ft |
| Attached (addition to primary home) | Greater of 50% of the primary dwelling's floor area, or 850 sq ft (1 bedroom or less) / 1,000 sq ft (2+ bedrooms) | 25 ft, or the height of the primary dwelling, whichever is greater | |
| Converted (garage, existing accessory structure, or space within the home) | Existing footprint, plus up to 150 sq ft of expansion for ingress/egress | Same as existing structure | Not subject to the standard new-construction setback rules |
| Junior ADU (JADU) | Up to 500 sq ft | Within the existing walls of the primary unit | Requires an owner-occupancy deed restriction |
ADUs are allowed in all residential, agricultural-residential, and agricultural zoning districts. A single-family lot can combine 1 detached ADU with 1 JADU, or build the ADU within the existing home. Lots with an existing multifamily building can add up to 8 detached ADUs (capped at the number of existing units) plus a conversion unit within up to 25% of existing units; lots with a proposed multifamily building are capped at 2 detached ADUs. Confirm your parcel's zoning with Development Services.
| Setbacks | 4 ft minimum interior side and rear yard for new construction; front and street-side setbacks follow the underlying zoning district. No additional setback for a conversion of existing living area or an existing accessory structure. |
| Parking | 1 additional off-street space required per bedroom, waived if the ADU is within a half-mile of public transit, in a historic district, part of the existing home or an existing accessory structure, or when on-street permits aren't available to the occupant or a car-share vehicle is within a block. Tandem parking on an existing driveway is allowed. |
| Units per lot | 1 detached ADU plus 1 JADU on a single-family lot (or one ADU/JADU combination within the existing home); up to 8 detached ADUs on a qualifying multifamily lot |
| Owner-occupancy | Not required for a standard ADU - both the primary home and the ADU can be rented out. A JADU requires the owner to occupy the primary unit or the JADU, waived for government agencies, land trusts, and housing organizations. |
| Building code | Must meet the current California Residential Code as adopted by the city; must be architecturally compatible with the primary dwelling. Fire sprinklers are only required if the primary home has them. |
| Solar | A PV solar system is required on newly constructed detached ADUs under the California Energy Code, though it can be installed on the ADU or added to the main house's existing system |
| Resale | An ADU generally can't be sold separately from the primary home, except as allowed under Government Code Section 65852.26 |
Worth knowing: as of the most recent update to the state's public ADU ordinance-review tracker, Elk Grove does not appear on HCD's list of cities that have received an ADU ordinance findings or non-compliance letter. Separately, the state has pursued Elk Grove in court over a denied affordable-housing project unrelated to ADUs - a reminder that a city's broader housing-approval record and its ADU ordinance specifically are two different things worth checking independently.
Call Planning at (916) 478-2256 to confirm your lot's zoning, or ask Building Safety & Inspection at (916) 478-2235 about the Over-the-Counter ADU Program's free pre-approved plans.
If using a pre-approved plan, schedule a joint meeting with Building, Planning, and Engineering to review your site plan and Title 24 energy documentation before submittal.
Custom projects need a full plan set; pre-approved plans need only a site-specific site plan showing property lines, utility locations, and distances to other structures.
Depending on your project, you may need sign-off from the Cosumnes CSD Fire Department, the local health department, or the school district before the permit issues.
Pre-approved plans can be issued over the counter once pre-approvals are complete; custom plans go through standard plan check, which state law caps at 60 days for a complete application.
The required PV solar system is permitted separately and must be completed before final inspection. Schedule standard framing, plumbing, and electrical inspections as work proceeds.
Fees and timelines are approximate - confirm current figures with Building Safety & Inspection before you apply.
| Garage conversion | Roughly $60,000-$150,000, the least expensive path since the shell already exists |
| New detached ADU | Roughly $130,000-$290,000 for a code-compliant, freestanding unit up to 1,200 sq ft, depending heavily on size and finishes |
| Pre-approved plan savings | The city's free Over-the-Counter plans (a studio, a 625 sq ft one-bedroom, and a 746 sq ft two-bedroom design) can cut design costs and shorten review versus a fully custom project |
| Impact fees | Waived for ADUs under 750 sq ft under statewide SB 13; new residential construction above that is subject to school district developer fees, paid directly to the applicable district |
These are general ranges from local contractor estimates and regional reporting, not quotes - actual cost depends heavily on lot conditions, finishes, and whether a parking space needs to be added. Elk Grove/Sacramento-area construction costs generally run below the Bay Area.
