Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your Huntington Beach ADU cost →Building an ADU in Huntington Beach costs between $185,000-$420,000 for new construction, with per-square-foot costs averaging $300-$525. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $90,000-$185,000, while prefab/modular ADUs fall in between at $120,000-$300,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | $40 processing plus an inspection fee set by city valuation (about $1,664 at $150,000), 61% building and 46% planning plan review, trade permits, and a 6% automation fee (Res. 2023-21); roughly $4,000-$6,000 for a 490-800 sq ft ADU. A Coastal Development Permit adds $5,756 (single-family lot) |
| Impact Fees | None for an ADU of 750 sq ft or less; larger units pay in proportion to the primary dwelling (Gov. Code 66311.5). The city's schedule lists an Accessory Dwelling Unit rate for units that do pay: park land $3,130, library $213, police $183.50 and fire $86 per unit (effective 10/1/2016, plus 6% automation), a traffic fee set by Public Works (714-536-5431), and a school fee of $4.79 per sq ft on residential additions of 500 sq ft or more |
| Site Prep & Foundation | $10,000 – $35,000 |
| Framing & Structure | $15,000 – $45,000 |
| Plumbing | $8,000 – $20,000 |
| Electrical | $5,000 – $15,000 |
| HVAC | $3,000 – $8,000 |
| Interior Finishes | $15,000 – $40,000 |
Quotes for the same ADU commonly vary 20–40% between builders. We pass your request to up to 5 local builders serving Huntington Beach, where we have them — free, no obligation.
Get Huntington Beach builder quotes →Permit fees in Huntington Beach are $40 processing plus an inspection fee set by city valuation (about $1,664 at $150,000), 61% building and 46% planning plan review, trade permits, and a 6% automation fee (Res. 2023-21); roughly $4,000-$6,000 for a 490-800 sq ft ADU. A Coastal Development Permit adds $5,756 (single-family lot). The review timeline is Building Division targets 20 business days for a first plan check (10 expedited at twice the fee), 10 for a second and 5 after that; state law requires a decision within 60 days of a complete application or the ADU is deemed approved (Gov. Code 66317, SB 543). A coastal permit adds months, with plan check: Digital submittal only (since February 1, 2023) through the HB ACA portal; over-the-counter review by appointment Monday and Wednesday mornings for very minor plans only. Plan review fees are due at submittal; more than two reviews on a project valued at $100,000 or less are billed at $162 per hour. Impact fees are None for an ADU of 750 sq ft or less; larger units pay in proportion to the primary dwelling (Gov. Code 66311.5). The city's schedule lists an Accessory Dwelling Unit rate for units that do pay: park land $3,130, library $213, police $183.50 and fire $86 per unit (effective 10/1/2016, plus 6% automation), a traffic fee set by Public Works (714-536-5431), and a school fee of $4.79 per sq ft on residential additions of 500 sq ft or more. Pre-approved plans: Yes: one free pre-approved plan under AB 1332 (Gov. Code 65852.27), a one-story 490 sq ft detached one-bedroom, one-bath ADU offered in three exteriors (California Ranch, Bungalow, Spanish Colonial), with an optional 53 sq ft porch and optional solar. The plan cannot be modified; sprinklers are required only if the main house has them, and the owner must check for an oil well on or within 100 ft of the parcel (methane barrier if yes).
| 1-Bedroom Rent | $2,600-$2,800/month |
| 2-Bedroom Rent | $3,050-$3,250/month |
| Annual Rental Income (est.) | $32,400/year |
| Payback Period (est.) | 9.3 years |
| Short-Term Rental | No for a new ADU. HB Municipal Code Chapter 5.120 (Ord. |
| Overall ROI Estimate | 7-12% gross annual yield |
A typical ADU in Huntington Beach generates approximately $32,400 per year in rental income based on average 1-bedroom rents. At an average construction cost of $302,500, the estimated payback period is 9.3 years — before accounting for the resale value the ADU adds, which an appraiser determines from comparable sales in Huntington Beach and varies by market (often less than build cost).
1. Garage conversions save 40-60% vs new construction since the shell already exists. Average cost in Huntington Beach: $90,000-$185,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $120,000-$300,000.
3. Pre-approved plans — available in Huntington Beach, which can save $3,000-$10,000 in design costs and 2-3 months in review time. See which cities offer pre-approved ADU plans.
4. State grants — California's CalHFA ADU grant (up to $40K) is currently paused; check calhfa.ca.gov/adu for status and your state for active programs.
5. Get multiple bids — ADU contractor pricing varies 20-40% for the same project. We recommend getting at least 3 quotes.
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