Colton ADU rules

Maximum size

A Class 2 (City standard) ADU, attached or detached, may be up to 850 sq ft for a studio or one bedroom and 1,200 sq ft for two or more bedrooms. An attached ADU on a lot with an existing home is also limited to 75% of the main home's floor area. Floor area ratio (45%), lot coverage (50%) and open space (50%) limits apply, but none of these, the 75% limit or the front setback can hold an ADU below 800 sq ft. A new detached ADU of up to 800 sq ft with 4 ft side and rear setbacks is allowed as a Class 1 ADU.

Source: Colton Ordinance No. O-07-26 amending Municipal Code § 18.48.150 Accessory Dwelling Units (City of Colton), § 18.48.150(e)(1)(B), (g)(1)-(2), (g)(4)-(5), accessed 2026-11-02.

Setbacks

New ADUs need 4 ft side and rear setbacks. A Class 2 ADU also needs a 25 ft front yard setback, but the front setback cannot hold an ADU below 800 sq ft. No setback is needed when an ADU is built in the same place and size as an existing structure, and converted Class 1 ADUs need only setbacks that meet fire and building codes.

Source: Colton Ordinance No. O-07-26 amending Municipal Code § 18.48.150 Accessory Dwelling Units (City of Colton), § 18.48.150(e)(1)(A)(iii), (e)(1)(B)(i), (g)(1)(C), (g)(3), accessed 2026-11-02.

Local ADU rules

Colton's ADU and JADU rules are in Municipal Code § 18.48.150, restated in full by Ordinance O-07-26, adopted April 7, 2026 and in effect 30 days later. It followed a temporary (urgency) Ordinance O-01-26 from February 2026. Every ADU and JADU needs a ministerial ADU permit and a building permit, with no hearing. The City says within 15 business days whether an application is complete and acts within 60 days of a complete application.

Source: Colton Ordinance No. O-07-26 amending Municipal Code § 18.48.150 Accessory Dwelling Units (City of Colton), § 18.48.150(d)(1), (d)(3); Ord. O-07-26 adopted Apr. 7, 2026, accessed 2026-11-02.

ADU types under state law (Class 1)

On a single-family lot: one converted ADU inside the home or an existing accessory structure (up to 150 sq ft added for entry and exit) plus one JADU, and also one new detached ADU of up to 800 sq ft of livable space with 4 ft side and rear setbacks. On a multifamily lot: converted ADUs in non-living space (at least one, up to 25% of existing units), plus detached ADUs with 4 ft side and rear setbacks (up to 8 on a lot with existing multifamily, not more than the number of existing units; up to 2 with proposed multifamily). All other ADUs are Class 2 and follow the City's own standards.

Source: Colton Ordinance No. O-07-26 amending Municipal Code § 18.48.150 Accessory Dwelling Units (City of Colton), § 18.48.150(e)(1)-(2), accessed 2026-11-02.

Height

A detached ADU may be 35 ft. Within a half mile walk of a major transit stop or high-quality transit corridor, a detached ADU may be two stories and 30 ft (plus 2 ft, up to 32 ft, to match the main home's roof pitch). On a lot with a multifamily building of more than one story, a detached ADU may be two stories and 30 ft. An attached ADU may be 35 ft or the zone's limit for the main home, whichever is lower, and no more than two stories. Height is measured from existing legal grade to the peak.

Source: Colton Ordinance No. O-07-26 amending Municipal Code § 18.48.150 Accessory Dwelling Units (City of Colton), § 18.48.150(f)(2), accessed 2026-11-02.

Parking

A Class 2 ADU needs one off-street space on the same lot, which may be in setback areas or tandem. No space is needed within a half mile walk of public transit, in a historic district, for an ADU inside the home or an existing accessory structure, where on-street permits are required but not offered, within one block of a car share stop, or when the ADU is filed with a new home or multifamily building and meets one of these tests. Garage, carport or uncovered spaces removed for an ADU need not be replaced. Access for a lot served by a panhandle or easement must be at least 20 ft wide.

Source: Colton Ordinance No. O-07-26 amending Municipal Code § 18.48.150 Accessory Dwelling Units (City of Colton), § 18.48.150(g)(7), accessed 2026-11-02.

Design, privacy and landscaping (Class 2 ADUs)

Class 2 ADUs must use the main home's wall, roof, window and door materials and colors and match its dominant roof slope, have down-lighting and their own exterior entrance, and be at least 10 ft wide inside with 7 ft walls. Windows and doors may not look directly onto a neighboring home's lot unless screened, and those less than 30 ft from a side or rear lot line must be clerestory or frosted. Evergreen screening plants (or a 6 ft solid fence) are required between the ADU and neighboring lots. An ADU on or within 600 ft of a property on the California Register of Historic Resources must not be visible from a public street.

Source: Colton Ordinance No. O-07-26 amending Municipal Code § 18.48.150 Accessory Dwelling Units (City of Colton), § 18.48.150(g)(8)-(10), accessed 2026-11-02.

Junior ADUs

A JADU may have up to 500 sq ft of interior livable space inside a single-family home (an attached garage counts), with an efficiency kitchen; if it shares a bathroom with the home, it needs an inside door to the home and its own outside entrance. An owner must live on the lot only when the JADU shares a bathroom with the home. A recorded deed restriction says the JADU cannot be sold separately and stays the size allowed.

Source: Colton Ordinance No. O-07-26 amending Municipal Code § 18.48.150 Accessory Dwelling Units (City of Colton), § 18.48.150(c)(5), (f)(7)(B), (f)(8), accessed 2026-11-02.

Fees, utilities, sprinklers and rentals

No impact fees for an ADU under 750 sq ft; larger ADUs pay in proportion to the main home's size. An ADU or JADU under 500 sq ft of interior livable space pays no school fees. Converted Class 1 ADUs on a single-family lot need no new utility connection or connection fee; other ADUs need a separate connection for City utilities, with a fee in proportion to their size or plumbing fixtures. Fire sprinklers are needed only if the main home needs them. No ADU or JADU may be rented for less than 30 days or sold separately. Owners report the expected rent with the certificate of occupancy and the actual rent each year.

Source: Colton Ordinance No. O-07-26 amending Municipal Code § 18.48.150 Accessory Dwelling Units (City of Colton), § 18.48.150(f)(3)-(5), (f)(9), (h), accessed 2026-11-02.

Septic systems

An ADU or JADU that will connect to a septic system needs a percolation test from the last 5 years (10 years if the test was renewed).

Source: Colton Ordinance No. O-07-26 amending Municipal Code § 18.48.150 Accessory Dwelling Units (City of Colton), § 18.48.150(f)(6), accessed 2026-11-02.

Planning contact

The Planning Division is at the Civic Center Annex, 659 N. La Cadena Drive, open 7:30 AM to 5 PM, Monday through Thursday (909-370-5079). The City posts an ADU/JADU planning application.

Source: City of Colton Planning Commission public hearing notice, DAP25-0047 ADU update, Notice of January 23, 2026, accessed 2026-11-02.