ADU Builder in Montebello, CA: Permits, Local Rules and Costs

How long does Montebello have to approve a complete ADU application?

State law sets the binding permit timeline. Under Gov. Code 66317(a)(3), a permitting agency shall approve or deny the application to create or serve an accessory dwelling unit within 60 days from the date the agency receives a completed application, and if the agency has not approved or denied the completed application within 60 days the application is deemed approved. Under Gov. Code 66317(a)(2), the permitting agency must tell the applicant in writing within 15 business days whether an ADU application is complete or what items are defective. The Montebello Planning Division Forms and Applications page on montebelloca.gov lists the ADU Quick Fact Sheet, the ADU/SFR Application, the City Fee Schedule, and the Walls and Fence Requirements handout as the documents a homeowner submits with a complete ADU application. The Planning Division Office Hours page on montebelloca.gov states that the Planning Division office is open Monday through Thursday, 7:30 AM to 5:30 PM, and is closed on Friday.

What detached ADU rules does the Montebello Fact Sheet require?

The City of Montebello Accessory Dwelling Units and Junior Accessory Dwelling Units Fact Sheet on montebelloca.gov states that, for single-family dwelling units within a residential or mixed-use zone, Montebello allows one of each of the following types of ADUs: one detached ADU, one ADU within the proposed or existing space of a single-family dwelling up to 1,200 square feet, and one Junior Accessory Dwelling Unit within the proposed or existing space of a single-family dwelling up to 500 square feet. The same Fact Sheet states that detached ADUs which are newly constructed from the ground up must have a 4 foot setback from the side and rear property lines and a 10 foot separation from any other building on the lot, or 5 feet with a 1 hour firewall throughout the entire accessory structure. The Fact Sheet caps the maximum size for a detached ADU at 1,200 square feet and the maximum height at 16 feet.

What parking rules apply to a Montebello ADU?

The Montebello ADU Fact Sheet on montebelloca.gov states that the maximum number of parking spaces the City requires is one parking space per ADU or per bedroom, whichever is less, unless the parking exemptions in California Government Code section 66322 apply. The same Fact Sheet lists the 66322(a) exemptions: ADUs within one-half mile walking distance of public transit, ADUs inside an architecturally and historically significant historic district, ADUs that are part of the proposed or existing primary residence or an accessory structure, projects where on-street parking permits are required but not offered to the ADU occupant, projects where a car share vehicle sits within one block of the ADU, and combined ADU and new dwelling applications on the same lot that satisfy any other 66322(a) criteria. The Fact Sheet states that local agencies may not require parking as a condition to permitting a JADU, even when the JADU is converted from an attached garage, citing Gov. Code 66334(a).

What impact fees apply to a Montebello ADU?

State law sets the impact fee floor that every California city has to allow. Under Gov. Code 66311.5(c)(1), a local agency, special district, or water corporation shall not impose any impact fee on an accessory dwelling unit that has 750 square feet of interior livable space or less or on a junior accessory dwelling unit that has 500 square feet of interior livable space or less, and any impact fees charged for an ADU of more than 750 square feet are charged proportionately in relation to the square footage of the primary dwelling. The City of Montebello City Fee Schedule on montebelloca.gov lists the planning and building permit fees the City charges for an ADU submittal. School district fees apply where the project exceeds the local district threshold, and utility connection fees are set by the providers named in the City application materials. L Square contacts the City Planning Department for the live fee totals before submittal.

What does a site need before a homeowner can build a Montebello ADU?

The Montebello ADU Fact Sheet on montebelloca.gov states that a JADU must be contained entirely within an existing or proposed single-family residence on a lot zoned for single-family residences, that the maximum size is no more than 500 square feet, that expansion beyond the physical dimensions of the existing residence is not allowed, that a JADU may share bathroom facilities with the primary residence but a separate kitchen is required, and that the owner must reside in either the remaining portion of the primary residence or in the newly created JADU. The Building and Safety Division page on montebelloca.gov states that complete ADU application requests must be submitted by email to the Building and Safety Division, and that incomplete applications may delay processing.

How much does a Montebello ADU cost from L Square?

L Square publishes configured model prices on the cost guide page: $180,000 for Model 600, $240,000 for each of Models 800A and 800B, $295,000 for each of Models 1000A and 1000B, and $354,000 for Model 1200. These are model prices, not a final lot total. Montebello lots also carry the City planning fee set by the City Fee Schedule on montebelloca.gov, the proportional impact fee on ADUs over 750 sq ft under Gov. Code 66311.5, school district fees where the project exceeds the district threshold, and any utility connection fees from the providers named in the City application materials. Garage conversions, attached ADUs, and JADUs are priced from a property specific scope because each one depends on the existing structure and the lot layout.

Official Montebello ADU sources

• The City of Montebello Planning Division Forms and Applications page on montebelloca.gov states that, for single-family dwelling units within a residential or mixed-use zone, Montebello allows one detached ADU, one ADU within the proposed or existing space of a single-family dwelling up to 1,200 square feet (a Converted ADU), and one Junior Accessory Dwelling Unit within the proposed or existing space of a single-family dwelling up to 500 square feet. Official source
• The City of Montebello ADU Quick Fact Sheet, published on montebelloca.gov and updated October 29, 2025, states that newly constructed detached ADUs must have a 4 foot setback from the side and rear property lines, a 10 foot separation from any other building on the lot, a maximum size of 1,200 square feet, and a maximum height of 16 feet. Official source
• The City of Montebello Planning Division page on montebelloca.gov states that the Planning Division office is open Monday through Thursday from 7:30 AM to 5:30 PM and is closed on Friday, and that the office accepts calls and emails for planning questions. Official source
• The City of Montebello Building and Safety Division page on montebelloca.gov states that complete ADU application requests must be submitted by email to the Building and Safety Division, and that incomplete applications may delay processing. Official source
• The City of Montebello City Fee Schedule page on montebelloca.gov is the public source for the planning fee, building permit fee, and impact fee amounts the City collects on an ADU submittal, and lists the current ADU application line items by fee type. Official source
• Gov. Code 66311.5(c)(1), hosted on leginfo.legislature.ca.gov, states that a local agency, special district, or water corporation shall not impose any impact fee upon the development of an accessory dwelling unit that has 750 square feet of interior livable space or less or a junior accessory dwelling unit that has 500 square feet of interior livable space or less, and that any impact fees charged for an ADU of more than 750 square feet shall be charged proportionately in relation to the square footage of the primary dwelling. Official source
• Gov. Code 66317(a)(3), hosted on leginfo.legislature.ca.gov, states that a permitting agency shall approve or deny the application to create or serve an accessory dwelling unit within 60 days from the date the agency receives a completed application if there is an existing single-family or multifamily dwelling on the lot, and that if the permitting agency has not approved or denied the completed application within 60 days, the application is deemed approved. Official source