San Diego, CA · Metro San Diego
ADU construction prices in San Diego, CA: 2026 ranges
An ADU construction in San Diego costs $315–$525 per sq ft, with a typical mid-size ADU running $95k–$189k. Small projects start around $63k; large or high-end work can reach $473k or more.
As of 2026, costs in San Diego run about 5% above the LA County baseline due to City of San Diego permitting, the coastal height limit, and older housing stock.
Updated
ADU Construction Cost by Size in San Diego
Totals adjusted for the San Diego market (1.05× LA County baseline). Ranges include labor, materials, permits, and contractor overhead.
| Size | Type | Range | Low | High |
|---|---|---|---|---|
| Small | JADU / studio | 150–400 sq ft | $63k | $137k |
| Medium | 1-bed garage conversion | 400–600 sq ft | $95k | $189k |
| Large | Detached 2-bed | 800–1,200 sq ft | $263k | $473k |
What Affects ADU Construction Cost in San Diego?
- ADU type (JADU vs attached vs detached).
- Site prep and grading.
- Utility connections.
- CA Title 24 energy compliance.
- City ADU permit timeline.
- San Diego market premium: local pricing reflects City of San Diego permitting, the coastal height limit, and older housing stock, which shifts totals about 5% above the LA County baseline.
Get exact ADU construction bids in San Diego
Two or three licensed builders who work in San Diego, pricing the same scope.
ADU Construction Sub-Type Comparisons
Garage Conversion ADU vs Detached ADU
Garage conversions reuse the existing slab and shell at $90k–$180k; a detached new-build ADU runs $250k–$450k but unlocks larger floor plans and higher rent.
Junior ADU (JADU) vs Attached ADU
A JADU (≤500 sq ft, within the home) runs $60k–$130k and shares utilities; an attached ADU is a true second unit at $150k–$350k with its own entrance and meter.
How to Get the Best Price on a ADU Construction in San Diego
- Get line-itemized bids from two or three builders on the same scope; San Diego ADU construction pricing commonly varies 10–25% between contractors.
- Lock major materials and finishes before signing; mid-project change orders are the #1 cost driver on ADU construction jobs.
- Bid in shoulder seasons (Jan–Mar or Sep–Oct) when San Diego contractor schedules are open and rush premiums disappear.
- Verify CSLB license, insurance, and bond before paying any deposit. California caps deposits at $1,000 or 10% of contract, whichever is less.
What is an ADU construction?
An accessory dwelling unit (ADU) is a second, self-contained home on a single-family lot, with its own kitchen, bathroom and entrance. It can be detached, attached to the main house, a converted garage, or a junior ADU of up to 500 sq ft inside the existing home.
How to get an accurate price
- 1.Write down the scope: size, any layout changes, the finish level, and who supplies fixtures and materials.
- 2.Get bids from two or three licensed builders who work in San Diego, all pricing that same ADU construction scope.
- 3.Line the bids up item by item. Check allowances, permits, exclusions, and whether overhead and profit are shown.
- 4.Before any deposit, check each builder's CSLB license and insurance. As of 2026, California caps a home improvement down payment at $1,000 or 10% of the contract, whichever is less, according to the Contractors State License Board.
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Questions about ADU Construction in San Diego
How much does an ADU construction cost in San Diego, CA?
An ADU construction in San Diego costs $63k–$473k, with a typical mid-size ADU running $95k–$189k. Per-unit pricing falls in the $315–$525 per sq ft range.
Do I need a permit for an ADU construction in San Diego?
Yes for most scopes — the city building department requires permits any time you move plumbing, gas, electrical, or alter structure. Like-for-like cosmetic refreshes generally don't.
How long does an ADU construction take in San Diego?
Plan for 4–14 weeks of construction in San Diego depending on size and complexity, plus 2–8 weeks for design, permits, and material lead times.
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