ADU Builder in Paramount, CA: Local Rules, Fees and Permits

How big can an ADU be on a Paramount lot?

Paramount's ADU FAQ handout sets the size limits for a lot with a single-family home. An ADU with 2 or more bedrooms can be up to 1,000 square feet, and an ADU with 1 bedroom or fewer can be up to 850 square feet. A junior ADU inside the primary home or an attached garage is up to 500 square feet. A converted ADU inside an existing structure can add up to 150 square feet for ingress and egress. A lot with a single-family home can carry one ADU and one JADU, and the handout says there is no minimum lot size, so a small lot is not automatically disqualified. Attached covered patios and attached garages do not count toward the living space limit.

How long does an ADU permit take in Paramount?

State law sets the backstop. A permitting agency must give written notice of whether an application is complete within 15 business days, approve or deny a complete application within 60 days, and treat a complete application it has not acted on in that window as approved. The city's own ADU process guide is faster on the first steps. It says planning applications are reviewed within 10 days and building permit projects within 10 business days, and that an inspection requested before 4:00 PM is scheduled the next available day, while a request after 4:00 PM is scheduled two business days later. Because the city is rewriting its ADU chapter in 2026, confirm current timing with the Planning and Building counter before you commit to a schedule.

What does the City of Paramount charge for an ADU permit?

An ADU application in Paramount is filed as an Administrative Action, and the city's planning fee schedule, effective February 1, 2025, lists the Administrative Action fee at $1,610.00 per application. Building and safety fees are separate and are set by project valuation. The city's process guide also notes that for ADUs of 500 square feet or more the permit includes Paramount School District fees. State law limits impact fees. No impact fee can be charged on an ADU with 750 square feet of interior living space or less, and above that size the fee has to be proportionate to the square footage of the primary dwelling.

How much does an ADU cost in Paramount?

L Square publishes configured model prices on its Orange County cost page: Model 600 at $180,000, Model 800A and Model 800B at $240,000 each, Model 1000A and Model 1000B at $295,000 each, and Model 1200 at $354,000. A 600 square foot unit is a 2 bed, 1 bath layout, the 800 square foot models are 2 bed and 2 bath, and the 1,000 and 1,200 square foot units are 3 bed and 2 bath. Those are unit prices, not a total for your lot. Site preparation, utility connections, structural engineering, permits and finish choices are quoted per property, and city fees sit on top of that list.

Does Paramount have pre-approved ADU plans I can build from?

The city runs a program called Plan-It Paramount, and the plans are free. Four plans are pre-reviewed and pre-approved by the Building and Safety Division: ADU-Studio at 447 square feet with 0 bedrooms and 1 bathroom, ADU-1 at 630 square feet with 1 bedroom and 1 bathroom, ADU-2 at 744 square feet with 2 bedrooms and 2 bathrooms, and ADU-3 at 1,000 square feet with 3 bedrooms and 2 bathrooms. The city says modifications are not allowed on these plans no matter how small the change, and any project that uses one still has to meet Chapter 17.104 of the zoning title for setbacks, building heights and building separation.

What should I check before building an ADU in Paramount?

Check the zoning first, because an ADU is legal on any property zoned for residential use. On utilities, the city does not require a separate direct connection between an ADU and the utility on an existing property, though a connection fee or capacity charge can apply when the ADU goes with a new single-family home. Expect a property tax increase for the ADU alone, not for the existing home. A rental has to run at least 30 days, and a junior ADU means the homeowner lives in either the primary home or the JADU. The city's process guide says planning applications are reviewed within 10 days, and you can submit an ADU plan set at the same time as a new house. Finally, the rules are moving: HCD reviewed the city's ADU ordinance, Ordinance No. 1191 adopted January 14, 2025, and on July 1, 2026 found it not compliant in several respects, with a written response due by July 31, 2026, and the city set a public hearing for October 27, 2026 on Ordinance No. 1220 to amend Chapter 17.104.

Official Paramount ADU sources

• The city ADU FAQ handout states that an ADU with 2 or more bedrooms can be up to 1,000 square feet, one with 1 bedroom or fewer up to 850 square feet, a junior ADU up to 500 square feet, a converted ADU can add 150 square feet for ingress and egress, one ADU and one JADU are allowed on a single-family lot with no minimum lot size, one parking space is required for a new ADU unless the lot is within a half mile of a transit stop or the ADU is a conversion, off-street spaces need not be replaced for a converted garage, and a new ADU or JADU cannot be rented for less than 30 days. Official source
• The city ADU Resources page describes the Plan-It Paramount program with four pre-reviewed and pre-approved plans, from ADU-Studio at 447 square feet with 0 bedrooms and 1 bathroom up to ADU-3 at 1,000 square feet with 3 bedrooms and 2 bathrooms, designed by the city and available at no cost, with no modifications allowed, and with projects still required to meet the city's ADU ordinance for setbacks, building heights and building separation. Official source
• The city planning fee schedule, effective February 1, 2025, lists Administrative Action at $1,610.00 per application. Official source
• The city directs ADU applicants to file an Administrative Action application online, and posts the Administrative Action Accessory Dwelling Unit application form and the planning fee schedule that took effect February 1, 2025. Official source
• The city requires each ADU plan set to include a title sheet, existing and proposed site plan, existing and proposed floor plan, mechanical, electrical, plumbing and structural sheets, Title 24 energy calculations and administrative action documentation, and it says inspections requested before 4:00 PM PST are scheduled the next available day while requests made after 4:00 PM PST are scheduled two business days later. Official source
• In a July 1, 2026 findings letter on the city's ADU ordinance, the California Department of Housing and Community Development said Ordinance No. 1191, adopted January 14, 2025, does not comply with state ADU law in several respects, gave the city 30 days to respond, and set July 31, 2026 as the deadline for a written response. Official source
• A public hearing notice for Ordinance No. 1220, Zoning Ordinance Text Amendment No. 44, posted October 1, 2026, sets a City Council hearing on Tuesday, October 27th, 2026 to amend Chapter 17.104 of Title 17 of the Paramount Municipal Code on accessory dwelling unit and junior accessory dwelling unit rules, citywide in residential zones. Official source
• The city's ADU process guide says a planning application is reviewed within 10 days, a building permit project is reviewed within 10 business days, permits for ADUs of 500 square feet or more include Paramount School District fees, and construction times vary with 6 to 12 months common. Official source
• California Government Code Section 66317 requires a permitting agency to give written notice of whether an accessory dwelling unit application is complete no later than 15 business days after receiving it, to approve or deny a completed application within 60 days, to treat a completed application it has not acted on in that time as approved, and to consider and approve an application ministerially without discretionary review or a hearing. Official source
• California Government Code Section 66314 provides that the total floor area for a detached accessory dwelling unit shall not exceed 1,200 square feet, that the total floor area for an attached accessory dwelling unit shall not exceed 50 percent of the existing primary dwelling, that parking shall not exceed one space per accessory dwelling unit or per bedroom, whichever is less, and that the local agency shall not require replacement parking when a garage, carport or covered parking structure is converted to an accessory dwelling unit. Official source
• California Government Code Section 66311.5 provides that a local agency shall not impose any impact fee on an accessory dwelling unit with 750 square feet of interior living space or less, and that impact fees for a larger accessory dwelling unit must be charged proportionately in relation to the square footage of the primary dwelling unit. Official source