San Mateo County

Pacifica ADU rules

Research summary of what we found for City of Pacifica in San Mateo County. Not a determination for a specific lot.

Last checked November 3, 2026.

City or county ADU page

How big can an ADU be in Pacifica?

Maximum size
A new detached ADU may be up to 1,200 sq ft. An attached ADU may be up to 850 sq ft (studio or one bedroom) or 1,000 sq ft (two or more bedrooms), or 50% of the main home's floor area if that is larger. An ADU inside existing space has no maximum, but must leave the main home at least the zone's minimum home size. An ADU of 800 sq ft or less has no lot coverage or landscaping limit. An ADU over 800 sq ft must meet the zone's lot coverage and landscaping limits and is not allowed on a lot that fronts an unpaved street or a street 26 ft wide or less.
Source: Pacifica Municipal Code Title 9, Ch. 4, Art. 4.5 Accessory Dwelling Units (Municode), § 9-4.453(c)(1), (5)-(7), (d)(1), (5)-(7), (e)(1), accessed 2026-11-03.

ADU setbacks in Pacifica

Setbacks
New detached and attached ADUs need 4 ft side and rear setbacks and a 15 ft front setback (20 ft for an attached ADU built over a garage). Under state law (Gov. Code § 66321(b)(3)), a front setback cannot block an 800 sq ft ADU with 4 ft side and rear setbacks. An ADU over 800 sq ft must be at least 10 ft from other buildings on the lot or next door; one of 800 sq ft or less has no spacing rule. No setback is needed for an ADU inside existing space or a rebuild in the same place and size.
Source: Pacifica Municipal Code Title 9, Ch. 4, Art. 4.5 Accessory Dwelling Units (Municode), § 9-4.453(c)(2)-(3), (d)(2)-(3), (e)(2), accessed 2026-11-03.

What we found for Pacifica

What we have for this place. Where a local figure is stricter than the California state baseline, both are shown.

Coastal Zone
Part of Pacifica is in the Coastal Zone. Pacifica's ADU rules apply in and out of the Coastal Zone, but a Coastal Zone ADU or JADU may also need an administrative coastal development permit, decided by the Planning Director without a hearing, before the building permit. Stricter parking rules apply in the coastal access parking areas (parts of Pacific Manor and Fairmont West, West Sharp Park, Rockaway Beach and Pedro Point). This lookup cannot tell whether a parcel is in the Coastal Zone or a coastal access parking area; check with the Planning Division.
Source: Pacifica Municipal Code Title 9, Ch. 4, Art. 4.5 Accessory Dwelling Units (Municode), §§ 9-4.453(h), 9-4.455(c), accessed 2026-11-03.

Local ADU rules
Pacifica's ADU rules are in Municipal Code Title 9, Chapter 4, Article 4.5 (§§ 9-4.451 to 9-4.456), last amended by Ordinance 867-C.S. (in effect September 22, 2021). ADUs are allowed on any lot zoned for homes, or zoned commercial where homes are allowed, that has a proposed or existing single-family home or an existing multifamily building. Review is ministerial: only a building permit is needed, plus a coastal permit in the Coastal Zone.
Source: Pacifica Municipal Code Title 9, Ch. 4, Art. 4.5 Accessory Dwelling Units (Municode), §§ 9-4.451(b), 9-4.453(a)(11), (b), accessed 2026-11-03.

Height
A detached ADU may be 25 ft or the main home's height, whichever is less. It is limited to 16 ft if any part is less than 5 ft from a side lot line, 10 ft from a street-side lot line or 20 ft from the rear lot line, if any part is between the main home and the front property line, or if the main home is under 16 ft. An attached ADU may be 35 ft when attached to the main home. ADUs inside existing space have no added height limit.
Source: Pacifica Municipal Code Title 9, Ch. 4, Art. 4.5 Accessory Dwelling Units (Municode), § 9-4.453(c)(4), (d)(4), (e)(5), accessed 2026-11-03.

Parking
Outside the coastal access parking areas, an ADU needs one space per ADU or per bedroom, whichever is less. No space is needed for a detached ADU of 800 sq ft or less, an attached ADU, an ADU inside existing space or on a multifamily lot, a studio, an ADU within a half mile of public transit (straight-line distance) or in a historic district, where on-street permits are required but not offered, or within one block of a car share vehicle. A garage converted or removed for an ADU need not be replaced. Inside a coastal access parking area, every ADU needs one space and all required spaces on the lot, including replaced garage spaces, must stay on site. Spaces may be uncovered, tandem, in setbacks, or on a lift. Junior ADUs need no parking.
Source: Pacifica Municipal Code Title 9, Ch. 4, Art. 4.5 Accessory Dwelling Units (Municode), §§ 9-4.453(h), 9-4.454(d), accessed 2026-11-03.

Junior ADUs
One JADU of up to 500 sq ft is allowed inside the existing or proposed space of a single-family home or accessory structure, with up to 150 sq ft added for entry. A shared bathroom does not count toward the 500 sq ft. It needs its own exterior entrance and a recorded deed restriction (the City has a form). It needs no parking, no separate utility connection, and no fire sprinklers unless the main home needs them.
Source: Pacifica Municipal Code Title 9, Ch. 4, Art. 4.5 Accessory Dwelling Units (Municode), § 9-4.454(a)(2)-(4), (9), (c)(1), (d)-(f), accessed 2026-11-03.

Utilities, sprinklers and renting
An ADU inside existing space needs no new utility connection or connection fee unless built with a new home. Other ADUs may need their own connection, with fees in proportion to the ADU's size or plumbing fixtures. Fire sprinklers are needed only if the main home needs them. ADUs and JADUs may be rented, but not for less than 30 days in a row, and may not be sold separately from the main home.
Source: Pacifica Municipal Code Title 9, Ch. 4, Art. 4.5 Accessory Dwelling Units (Municode), §§ 9-4.453(a)(5)-(7), (i), (j), 9-4.454(a)(6)-(7), accessed 2026-11-03.

Plans and help
The City's ADU page links a lot lookup tool, a Second Unit Resource Center workbook, and an ADU plans gallery with ready-made designs; the City says plans reviewed in advance can cut building permit review to 30 days. Planning Division: (650) 738-7341, planningdivision@pacifica.gov.
Source: City of Pacifica, Accessory Dwelling Units, Accessory Dwelling Units page, accessed 2026-11-03.

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.

Starting January 1, 2027: two detached ADUs
Starting January 1, 2027, AB 956 (Chapter 791, Statutes of 2026) raises from one to two the number of new detached ADUs a city or county must allow, without discretionary review, on a lot with a proposed or existing single-family home (Gov. Code 66323(a)). Each may be held to 800 sq ft, 4 ft side and rear setbacks and the state height limits. The city or county does not have to also allow a JADU on a lot where two new detached ADUs have been built. AB 956 also makes HOA and deed rules that effectively prohibit or unreasonably restrict an ADU or JADU void on any lot zoned to allow a single-family home, not only lots zoned for single-family use (Civil Code 4751 and 714.3).
Source: AB 956 (2025-2026), Chapter 791, Statutes of 2026, Gov. Code 66323; Civil Code 714.3, 4751; signed September 29, 2026, accessed 2026-11-03.

Starting January 1, 2027: impact fees above 750 sq ft
No impact fee may be charged on an ADU of 750 sq ft or less, or a JADU of 500 sq ft or less (Gov. Code 66311.5(c)). Starting January 1, 2027, SB 1117 (Chapter 809, Statutes of 2026) changes how fees are figured for larger ADUs: for up to two ADUs on a lot, the proportional impact fee is charged only on the interior livable space above 750 sq ft. On a lot with more than two ADUs, the fee stays proportional to the whole ADU. Utility connection fees and capacity charges are not changed.
Source: SB 1117 (2025-2026), Chapter 809, Statutes of 2026, Gov. Code 66311.5(c); signed September 29, 2026, accessed 2026-11-03.

State baseline on the directory → · State ADU rules on the homepage →

ADU rules near Pacifica

San Bruno · about 3 miles
Burlingame · about 7 miles
Brisbane · about 7 miles
Town of Hillsborough · about 8 miles
San Francisco · about 11 miles

Can I build an ADU in Pacifica?

State law sets a baseline for ADUs in Pacifica, 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 City of Pacifica Planning Division, or run a free address summary.

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