Sacramento County

Folsom ADU rules

Research summary of local ADU rules on file for Folsom in Sacramento County. Not a determination for a specific lot.

Last checked October 24, 2026.

City or county ADU page

Folsom rules on file

Local rules recorded in this project for this jurisdiction. Where a city figure on file is stricter than the state baseline on file, both are shown.

Local ADU rules
Folsom's ADU and JADU rules are in Municipal Code Chapter 17.105, rewritten by Ordinance 1361 (2026). ADUs are allowed on lots zoned for single-unit, two-unit or multi-unit homes with an existing or proposed main home; JADUs on lots zoned for single-unit homes.
Source: Folsom Municipal Code Ch. 17.105 Accessory Dwelling Units (Code Publishing), § 17.105.010, accessed 2026-10-24.

Review times
The City says within 15 business days whether an application is complete, and acts on a complete application within 60 days. If it denies an application it gives written comments within 60 days. Appeals go to the Planning Commission.
Source: Folsom Municipal Code Ch. 17.105 Accessory Dwelling Units (Code Publishing), § 17.105.050, accessed 2026-10-24.

Number of units
Unit counts follow Gov. Code § 66323. On a lot created by an SB 9 lot split, no more than two units in total (including ADUs and JADUs) are allowed.
Source: Folsom Municipal Code Ch. 17.105 Accessory Dwelling Units (Code Publishing), § 17.105.120, accessed 2026-10-24.

Attached ADUs
Attached ADUs: up to 850 sq ft (one bedroom or less) or 1,000 sq ft (two or more bedrooms), and no more than 50% of the main home, with 4 ft side and rear setbacks and the zone's front setback. No standard can block at least an 800 sq ft ADU with 4 ft side and rear setbacks.
Source: Folsom Municipal Code Ch. 17.105 Accessory Dwelling Units (Code Publishing), § 17.105.140, accessed 2026-10-24.

Detached ADUs
A new detached ADU up to 800 sq ft with 4 ft side and rear setbacks and state height limits (Gov. Code § 66321) qualifies under § 66323. Other detached ADUs may be up to 850 sq ft (one bedroom or less) or 1,000 sq ft (two or more bedrooms), with 4 ft side and rear setbacks, at least 6 ft from other buildings, behind the front plane of the main home, and covering no more than 40% of the rear yard; none of these may block an 800 sq ft ADU with 4 ft side and rear setbacks.
Source: Folsom Municipal Code Ch. 17.105 Accessory Dwelling Units (Code Publishing), § 17.105.150, accessed 2026-10-24.

Junior ADUs
Owner occupancy for a JADU is required only when it shares sanitation facilities with the main home; it is not required when the JADU has its own bathroom or the owner is a public agency, land trust or nonprofit housing group.
Source: Folsom Municipal Code Ch. 17.105 Accessory Dwelling Units (Code Publishing), § 17.105.160, accessed 2026-10-24.

Multifamily lots
Two-unit and multi-unit lots may add converted ADUs and detached ADUs as allowed by Gov. Code § 66323, with 4 ft side and rear setbacks; no design standards apply to these units.
Source: Folsom Municipal Code Ch. 17.105 Accessory Dwelling Units (Code Publishing), § 17.105.170, accessed 2026-10-24.

Parking
One added space per ADU or per bedroom, whichever is less, with no parking required near transit (half mile walk), in the historic district, for units inside the main home or an existing accessory building, where on-street permits are not offered, near car share, or when built with a new home. Replacement parking is not required.
Source: Folsom Municipal Code Ch. 17.105 Accessory Dwelling Units (Code Publishing), § 17.105.180, accessed 2026-10-24.

Fees, rentals and sale
No impact fees for ADUs of 750 sq ft or less. ADUs and JADUs may not be rented for terms of 30 days or less. An ADU may be sold separately to a qualified buyer under Gov. Code § 66341.
Source: Folsom Municipal Code Ch. 17.105 Accessory Dwelling Units (Code Publishing), §§ 17.105.060, 17.105.070, accessed 2026-10-24.

Design standards
Objective design standards apply citywide and in historic district zones; an applicant may ask the Community Development Director for a design review to deviate from them.
Source: Folsom Municipal Code Ch. 17.105 Accessory Dwelling Units (Code Publishing), §§ 17.105.110, 17.105.190, 17.105.200, accessed 2026-10-24.

California state rules on file

The statewide baseline recorded from state law and the HCD ADU Handbook.

Detached size cap described in state law
1,200 sq ft. Recorded in this rules file 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. Recorded in this rules file 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, as recorded in this rules file 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, as recorded in this rules file 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. Recorded in this rules file 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. Recorded in this rules file 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. Recorded in this rules file 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. This rules file 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 Folsom?

State law sets a baseline for ADUs in Folsom, and the local standards on file are 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 City of Folsom Community Development Department, or run a free address summary.

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