An ADU builder in Pasadena is a licensed contractor who designs and constructs accessory dwelling units — detached backyard units, garage conversions, attached additions, and junior ADUs (JADUs). Because an ADU is a complete second dwelling, the builder coordinates foundation, framing, plumbing, electrical, and HVAC work and pulls it through Pasadena's permit process and utility connections. Not every general contractor has built one, so the right builder is one with ADU-specific experience in California.
What ADU Builders Cost in Pasadena [11][12]
Based on our Pasadena cost data, expect the following ranges from local ADU builders. Quotes for the same scope typically vary 20-40% between contractors, so getting at least three bids is the single best way to control cost.
| New Detached ADU (all-in) | $150,000-$400,000 |
| Cost per Sq Ft | $300-$450 |
| Garage Conversion | $120,000-$190,000 |
| Prefab / Modular ADU (installed) | $180,000-$300,000 |
| City Permit & Plan Review | Valuation-based (FY2027 General Fee Schedule, adopted June 8, 2026): building permit $1,738 plus $6 per $1,000 over $100,000; plan check $2,607 plus $9 per $1,000; Construction Tax 1.92%; General Plan and Technology fees 0.5% each; refundable C&D deposit flat $1,000; new address $345. |
| Impact Fees | Residential Impact Fee (PMC 4.17.050) is waived for ADUs of 900 sq ft or less and for any ADU with an executed Housing Agreement (effective July 17, 2025). A larger ADU pays a share of the per-unit fee (FY2027: $24,530 studio to $45,407 five-bedroom) prorated by ADU size against the main house. ADUs of 750 sq ft or less are also exempt under Gov. Code 66311.5. |
For a full line-item breakdown, see our Pasadena ADU cost guide. To confirm what you're allowed to build before you hire, review the Pasadena ADU rules (max detached size: 1,200 sq ft for a new detached ADU on a single-family lot (17.50.275.D.1.a). Hillside Overlay lots outside HD-1: 1,000 sq ft, or 800 sq ft where the street pavement is 26 ft wide or narrower (D.1.b). Conversions of existing space have no size limit. Floor area may be measured by the Zoning Code or the California Building Code, whichever the applicant prefers (D.1.d).; owner-occupancy: None for ADUs. A JADU that shares a bathroom with the main house requires the owner to live in either unit and a recorded covenant before permit issuance (17.50.275.E.3, E.5); a JADU with its own bathroom has no owner-occupancy rule, consistent with AB 1154 (eff. Jan 1, 2026).).
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How to Vet an ADU Builder in Pasadena
- License: Confirm a current contractor's license in California and that it's in good standing. Ask for the license number and verify it with the state board.
- ADU-specific experience: Ask how many ADUs they've completed in or near Pasadena and request addresses or photos. ADU permitting and setbacks differ from a kitchen remodel.
- Portfolio & references: Get references from recent ADU clients and, if possible, visit a finished unit.
- Insurance: Verify general liability and workers' compensation coverage. Ask for a certificate of insurance.
- Written, detailed bid: Insist on an itemized, fixed-price or clearly-scoped bid — not a verbal estimate. It should state whether permits (Valuation-based (FY2027 General Fee Schedule, adopted June 8, 2026): building permit $1,738 plus $6 per $1,000 over $100,000; plan check $2,607 plus $9 per $1,000; Construction Tax 1.92%; General Plan and Technology fees 0.5% each; refundable C&D deposit flat $1,000; new address $345.), plan check (Plan check is 50% off for ADUs using a city Standard Plan or with a Housing Agreement (affordability covenant or landlord agreement), and those units also skip the Construction Tax, General Plan Maintenance and Technology fees. ADUs of 900 sq ft or less without an agreement get 25% off those three items. Single-family sites only; reductions are not retroactive (effective May 6, 2025).), and impact fees (Residential Impact Fee (PMC 4.17.050) is waived for ADUs of 900 sq ft or less and for any ADU with an executed Housing Agreement (effective July 17, 2025). A larger ADU pays a share of the per-unit fee (FY2027: $24,530 studio to $45,407 five-bedroom) prorated by ADU size against the main house. ADUs of 750 sq ft or less are also exempt under Gov. Code 66311.5.) are included.
- Permit handling: Confirm they manage Pasadena's permit process ("Ministerial staff review with no hearing (17.50.275.A.2). Apply and upload plans through the Citizen Self-Service permit portal; a free virtual zoning consultation is offered before submittal. Each ADU needs its own address application. Intake asks whether you use a Standard Plan, will sign a Housing Agreement, and whether the unit is 900 sq ft or less, which sets your fee reductions.", typically 60 days from a complete application for the city to act, or the ADU is deemed approved (Gov. Code 66317; SB 543 from Jan 2026). For Standard Plan submittals the city publishes about 3-4 weeks for first plan check and about 2 weeks per resubmittal.) and who is responsible if revisions are required.
- Payment schedule: Avoid large upfront payments. A reasonable schedule ties payments to completed milestones.
Questions to Ask Before You Hire
- How many ADUs have you built in Pasadena in the last two years?
- Is your bid fixed-price, and what would trigger a change order?
- Are permits, plan check, and utility connection fees included?
- What's a realistic timeline, including permit review (60 days from a complete application for the city to act, or the ADU is deemed approved (Gov. Code 66317; SB 543 from Jan 2026). For Standard Plan submittals the city publishes about 3-4 weeks for first plan check and about 2 weeks per resubmittal.) and construction?
- Who is my point of contact and how are delays communicated?
- What warranty do you provide on workmanship?
- Can you share three recent California ADU client references?
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