An ADU builder in Upland 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 Upland'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 Upland [10][11][12][13][14]
Based on our Upland 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) | $175,000-$350,000 |
| Cost per Sq Ft | $180-$350 |
| Garage Conversion | $75,000-$150,000 |
| Prefab / Modular ADU (installed) | $120,000-$250,000 |
| City Permit & Plan Review | ADU permit fee set by Council resolution (§ 17.37.040(B)); the city's April 2023 guidebook listed $810, plus building permit/plan check typically $3,000-$4,000 and a $189 county fire letter. 2026 amounts not published online; confirm with Building & Safety, (909) 931-4110. |
| Impact Fees | None for ADUs of 750 sq ft or less of interior livable space (Gov. Code 66311.5; § 17.37.070(A)); at 750 sq ft and above they are charged in proportion to the primary home's floor area (city guidebook: $30,532 for a full-fee ADU in 2023). Conversions on single-family lots pay no water/sewer connection or capacity charge; new-construction ADUs pay a proportionate one (§ 17.37.070(B)). School fees apply from 500 sq ft (Upland USD; $4.08/sq ft in 2023). |
For a full line-item breakdown, see our Upland ADU cost guide. To confirm what you're allowed to build before you hire, review the Upland ADU rules (max detached size: Building permit only: one detached new ADU of 800 sq ft or less (§ 17.37.040(A)(2)). ADU permit: 850 sq ft for a studio/1-bedroom, 1,000 sq ft for 2+ bedrooms (§ 17.37.060(A)); no lot-coverage, FAR, front-setback or open-space rule may push the ADU below 800 sq ft.; owner-occupancy: Not required for ADUs created on or after January 1, 2020 (§ 17.37.050(G)(1)); required for JADUs, with the owner living in the house or the JADU (§ 17.37.050(G)(2); Gov. Code 66333-66339)).
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How to Vet an ADU Builder in Upland
- 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 Upland 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 (ADU permit fee set by Council resolution (§ 17.37.040(B)); the city's April 2023 guidebook listed $810, plus building permit/plan check typically $3,000-$4,000 and a $189 county fire letter. 2026 amounts not published online; confirm with Building & Safety, (909) 931-4110.), plan check (Planning checks Chapter 17.37 (zoning, size, setbacks, design); Building & Safety checks the California Building/Residential Codes as amended by Ordinance 2004 (Nov 24, 2025); San Bernardino County Fire issues a residential fire letter ($189 in 2023). Sprinklers only if the main house has them (§ 17.37.050(C)). Applications go through the city's CSS online portal.), and impact fees (None for ADUs of 750 sq ft or less of interior livable space (Gov. Code 66311.5; § 17.37.070(A)); at 750 sq ft and above they are charged in proportion to the primary home's floor area (city guidebook: $30,532 for a full-fee ADU in 2023). Conversions on single-family lots pay no water/sewer connection or capacity charge; new-construction ADUs pay a proportionate one (§ 17.37.070(B)). School fees apply from 500 sq ft (Upland USD; $4.08/sq ft in 2023).) are included.
- Permit handling: Confirm they manage Upland's permit process ("Ministerial, no hearing (§ 17.37.040(C)). Building permit only for the § 17.37.040(A) categories (conversions; one detached ADU of 800 sq ft or less at 16 ft with 4-ft side/rear setbacks; multifamily conversions and detached units); everything else also needs an ADU permit with the § 17.37.060 design standards (matching roof slope and materials, 12-inch eaves, 10-ft minimum interior width, no direct window sight lines, down-lighting, drought-tolerant landscaping, no roof decks). A garage demolition permit is issued with the ADU permit. Deed restriction recorded before the certificate of occupancy (§ 17.37.050(H) — HCD's July 8, 2025 letter found this unlawful for ADUs). Rent reporting: projected annual rent with the building permit, then actual rent within 90 days after each January 1 (§ 17.37.050(I)).", typically 60 days from a complete application, deemed approved if the city does not act (§ 17.37.040(C)); the city's 2023 guidebook adds 15-21 working days for the San Bernardino County Fire residential fire letter. No current published averages.) 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 Upland 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, deemed approved if the city does not act (§ 17.37.040(C)); the city's 2023 guidebook adds 15-21 working days for the San Bernardino County Fire residential fire letter. No current published averages.) 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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