Cost to Build ADU San Diego
Knowing the costs of building an ADU lets you plan smart, prevent unexpected expenses, and get the most value from your investment.
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What Affects ADU Cost San Diego
Your ADU’s cost can change a lot depending on a few key things. Knowing these can help you plan well and avoid surprises. Here are four main factors that impact ADU cost in San Diego:
Type of ADU You’re Building
Detached ADUs usually cost more than garage conversions or attached units. The design, complexity, and size all play a role.
Site Conditions
Sloped lots, old utility lines, or tricky access points can raise construction and preparation costs.
Material & Finish Choices
High-end finishes, custom cabinetry, or unique designs will increase the price. More basic finishes can save money.
Labor & Market Trends
Building costs in San Diego have gone up because of fewer workers and higher prices for materials. Prefab and modular ADUs reduce expenses and make construction more budget-friendly.
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Average Cost of ADU in San Diego
Cost Breakdown
Average ADU Construction Cost
Cost per Square Foot
Permitting and Fees
Additional Site Work (if applicable)
Amount
$275,000
$300 - $350
$5,000 - $15,000
$10,000 - $25,000
Cost Breakdown
Average ADU Construction Cost
$275,000
Cost per Square Foot
$300 - $350
Permitting and Fees
$5,000 - $15,000
Additional Site Work (if applicable)
$10,000 - $25,000
Understanding ADUs
ADU Permit Cost San Diego
Permit costs can have a big impact on your budget. They vary based on the type of ADU you build and your property’s size or condition. Things like square footage, whether it’s attached or detached, and utility needs all affect the price. Here’s a quick look at ADU permit cost in San Diego by unit type:
Attached ADU
$5,000 – $9,000. Shares a wall with your main home. Usually costs less to get permitted than a detached unit.
Conversion ADU
$4,000 – $8,000. Turns an existing garage into living space. Often cheaper than building from scratch but depends on the structure’s condition.
Detached ADU
$7,000 – $12,000. A stand-alone structure. Requires more in-depth review and sometimes extra fees for impact or utility hookups.
Junior ADU (JADU)
$1,500 – $4,000. A small unit (up to 500 sq. ft.) within the existing home. Costs less because it’s smaller and needs fewer changes to utilities and structure.
Cost Estimate
The average cost of an ADU in San Diego depends on the size, design, materials, and layout of your property. Try our calculator to get a personalized estimate based on your plans.
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Cost to Convert Garage to ADU Los Angeles Q/A
Why is San Diego ADU construction pricing so high?
Labor shortages, permitting complexities, and high demand all contribute. Still, ADUs are one of the most cost-effective ways to add livable space.
Can a prefab unit help lower the ADU cost San Diego?
Yes, prefab and modular ADUs build faster and cost less because they use standard materials and designs.
Is financing available for ADU projects in San Diego?
Yes. Many San Diego homeowners use HELOCs, construction loans, or ADU-specific financing to help manage costs.
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With the right plan and ADU Scale by your side, your garage conversion can become a cozy home, functional workspace, or income-generating rental.
More information
When planning your cost to build an ADU in San Diego, don’t forget about extra expenses. Utility upgrades, soil tests, surveys, and HOA approvals can add $10,000 to $30,000 or more. These hidden costs surprise many homeowners, so it’s smart to include them in your budget early.
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