Placer County
Unincorporated Placer County ADU rules
Research summary of what we found for Unincorporated Placer County in Placer County. Not a determination for a specific lot.
City or county ADU page
Unincorporated Placer County ADU page
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Maximum size
An ADU that is not one of the state-required types (larger than 800 sq ft, or attached) may have 850 sq ft of livable space, or 1,200 sq ft with more than one bedroom. An attached ADU may also be no more than 50% of the existing home, but at least 800 sq ft. Exterior walls, utility chases and equipment closets are not counted, within limits.
Source: Placer County Code § 17.56.200 Accessory and junior accessory dwelling units (eCode360; Ord. 6363-B, Feb. 17, 2026; Ord. 6392-B, Aug. 25, 2026), § 17.56.200(D)(2), (F)(2), accessed 2026-11-01.
What we found for Placer County
What we have for this place. Where a local figure is stricter than the California state baseline, both are shown.
Local ADU rules
County rule: The County's ADU and JADU rules are in County Code § 17.56.200, rewritten in 2026 (Ordinances 6363-B and 6392-B, the latter adopted August 25, 2026). The section mostly applies state ADU law directly: ADUs that meet the state-required types get a ministerial building permit, and height, parking and most other standards follow state law. The County adds its own size limits for larger ADUs.
Source: Placer County Code § 17.56.200 Accessory and junior accessory dwelling units (eCode360; Ord. 6363-B, Feb. 17, 2026; Ord. 6392-B, Aug. 25, 2026), § 17.56.200(A), (C)-(D), (F)(1), accessed 2026-11-01.
Other County standards
One parking space per ADU unless state law exempts it. Rentals must be 31 days or more, and ADUs and JADUs may not be sold separately except as state law allows. Fire sprinklers are needed only if the main home has them. Owner occupancy follows state law.
Source: Placer County Code § 17.56.200 Accessory and junior accessory dwelling units (eCode360; Ord. 6363-B, Feb. 17, 2026; Ord. 6392-B, Aug. 25, 2026), § 17.56.200(F)(3)-(7), accessed 2026-11-01.
Lake Tahoe Basin parcels
In the Lake Tahoe Basin, the Tahoe Regional Planning Agency (TRPA) reviews ADU applications under its Regional Plan first, and then the County issues its permit. TRPA checks land coverage for every ADU. An ADU needs a residential unit of use; a free bonus unit may be available near qualifying transit, in a Town Center or in a multifamily zone if the home or ADU is deed-restricted against tourist use and to set income levels. ADUs and JADUs may not be rented for 30 days or less.
Source: Placer County, Building Accessory Homes in Tahoe, accessed 2026-11-01.
State housing department (HCD) review
On December 5, 2025, HCD sent the County a technical assistance letter. It said the newest County ADU ordinance on file with HCD is from 2020 and may be out of date with state ADU law, and it listed the 2024 and 2025 state law changes (such as JADU owner occupancy only with a shared bathroom, impact fee limits, 15 business days to decide if an application is complete, and the number of ADUs allowed on a single-family lot). The letter sets no response deadline. The County rewrote its ADU rules in 2026 (Ordinances 6363-B and 6392-B).
Source: HCD technical assistance letter to Placer County, Letter of December 5, 2025, accessed 2026-11-01.
California state rules
The statewide baseline recorded from state law and the HCD ADU Handbook.
Detached size cap described in state law
1,200 sq ft. From Government Code section 66314.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.
Side and rear setback cap for a new ADU
4 ft. From Government Code section 66314, which describes a cap on side and rear setbacks for a new ADU.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.
Setback for a conversion of an existing structure
No additional setback, from Government Code section 66314 for a conversion of an existing structure.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.
Minimum lot size
A city may not impose a minimum lot size for an ADU, from Government Code section 66314.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.
Minimum unit the handbook says cities must allow
At least an 800 sq ft ADU with 4 ft side and rear setbacks. The HCD ADU Handbook (updated March 2026) describes this under section 66321(b)(3).
Source: HCD ADU Handbook, 66321(b)(3); handbook updated March 2026, accessed 2026-10-16.
Detached height described in the handbook
16 ft, or 18 ft or 20 ft in some cases. The HCD ADU Handbook (updated March 2026) describes this under section 66321(b)(4).
Source: HCD ADU Handbook, 66321(b)(4); handbook updated March 2026, accessed 2026-10-16.
Permit decision deadline
60 days. From Government Code section 66317(a)(3): the permitting agency must decide on (approve or deny) a completed ADU application within 60 days when an existing single-family or multifamily dwelling is on the lot. Section 66317(a)(1) says the application is considered ministerially, without discretionary review or a hearing.
Source: California Government Code section 66317, 66317(a)(1), (a)(3), accessed 2026-10-17.
Owner-occupancy requirement
None. From Government Code section 66315: a local agency may not impose an owner-occupancy requirement on an ADU. It may require that the property be used for rentals of terms 30 days or longer. The HCD ADU Handbook (updated March 2026) describes the same rule.
Source: California Government Code section 66315, 66315; HCD ADU Handbook updated March 2026, accessed 2026-10-17.
Parking near public transit
No parking standards within one-half mile walking distance of public transit. From Government Code section 66322(a)(1). Section 66322(a) lists several other cases where parking standards may not be imposed.
Source: California Government Code section 66322, 66322(a), accessed 2026-10-17.
Ministerial categories
The HCD ADU Handbook (updated March 2026) states that Government Code section 66323 sets four ministerial categories. What we have does not restate those four categories.
Source: HCD ADU Handbook, 66323; handbook updated March 2026, accessed 2026-10-16.
Fire Hazard Severity Zones
If your lot is in a Fire Hazard Severity Zone, the CAL FIRE Office of the State Fire Marshal says in Information Bulletin 25-004 (issued March 3, 2025): “Fire Hazard Severity Zones (FHSZs) should not restrict the development of Accessory Dwelling Units (ADUs). However, additional building standards may be necessary, including but not limited to California Fire Code Chapter 49 and California Building Code Chapter 7A.” State ADU law does not itself bar an ADU there. A city or county may still apply its building code, including wildfire-resistant construction (Gov. Code 66314(d)(8)); require side and rear setbacks “sufficient for fire and safety” for a unit converted under 66323(a)(1); and decline parking in setbacks on specific fire and life safety findings (66314(d)(10)(B)). It may also consider public safety when it designates where ADUs may be permitted (66314(a)). Sprinklers can't be required in an ADU or JADU if the primary residence doesn't need them (66314(d)(12), 66323(d)). Some cities and counties still apply their own fire-zone limits. Where this summary has one, it is listed with the local rules. This summary does not look up your lot. Check the CAL FIRE Fire Hazard Severity Zone map viewer linked from the State Fire Marshal's Fire Hazard Severity Zones page: https://experience.arcgis.com/experience/5065c998b4b0462f9ec3c6c226c610a9
Source: CAL FIRE Office of the State Fire Marshal Information Bulletin 25-004, page 4, issued March 3, 2025; Gov. Code 66314, 66323, accessed 2026-10-20.
State baseline on the directory → · State ADU rules on the homepage →
Can I build an ADU in Unincorporated Placer County?
State law sets a baseline for ADUs in Unincorporated Placer County, and what we found locally is listed on this page. Whether a specific lot can add an ADU depends on zoning, utilities, and other site facts this page does not measure. Confirm with the County of Placer planning department, or run a free address summary.
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