What is the 2026 cost range for a interior conversion scope adu in San Diego?

$121,500-$256,500, with the median landing near $189,000. The range reflects finish tier and layout complexity within the interior conversion scope; the San Diego labor multiplier of 1.35× vs national median is baked in.

How long does a interior conversion scope adu take in San Diego?

14-20 weeks of on-site construction for the interior conversion scope, plus 6-14 weeks of permit review in San Diego if the scope requires a permit. Cosmetic-only refreshes often skip permits; anything touching plumbing, electrical, or structural does not.

What is the single biggest budget-overrun risk for this scope?

Existing slab without a vapor barrier — vapor-pressure moisture leads to flooring failure and mold if not re-poured or sealed. Adds $4-8K.

ADU — Interior conversion Cost in San Diego, 2026

Low

$122K

$121,500

Median

$189K

$189,000

High

$257K

$256,500

Scope timeline: 14-20 weeksSan Diego permit window: 6-14 weeksUpdated 2026-04-24

Why interior conversion × San Diego produces this band

A interior conversion scope for a adu in San Diego combines two price levers: scope and metro labor rates. Interior-conversion ADUs repurpose an existing enclosed space (attached garage, basement) without adding foundation or framing footprint. Faster and cheaper than a detached build. Against the national median remodel labor rate, San Diego runs 35% above the national median — so the interior conversion band comes in 50% below the mid-range, then scales 35% above the national median on top of that. Permit timelines for residential work in San Diego typically run 6-14 weeks, which is the window you plan your design and decision sequence against. This page gives you the actual 2026 San Diego bands for this exact combination, plus the three cost drivers Baily asks about first when scoping the project live.

What drives cost for a interior conversion scope

·Insulation and conditioned-space HVAC tie-in
·Egress window cutting and well install
·Kitchen and bath rough-ins (often net-new to the space)
·Legal separation from the primary unit

What makes San Diego different

Labor — CSLB-licensed GC market with strong ADU-construction demand following SB 9 and SB 10.
Labor — Coastal Commission jurisdiction adds project-management time for parcels west of the 1st public road.
Labor — Military-base proximity generates steady remodel demand (off-base housing), keeping trades busy year-round.
Material — Title 24 energy requirements same as LA — higher envelope + glazing spec.
Material — Coastal corrosion protection required on hardware and fasteners within 1,500 ft of the ocean.

San Diego rules that affect this scope

San Diego Development Services Department (DSD) handles plan check — timeline varies by review type and discretionary vs ministerial.
Coastal Development Permit required within the Coastal Zone — adds 4-12 weeks.
San Diego ADU Bonus Program allows additional ADUs above state minimums with deed-restricted affordability.
Fire-prone hillside parcels subject to ember-resistant construction under Chapter 7A of California Building Code.

Scope your adu with Baily.

Baily asks the eight questions that determine where your project lands inside the $122K-$257K band for San Diego and hands the scoped brief to one licensed builder.

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Questions LA homeowners actually ask

$121,500-$256,500, with the median landing near $189,000. The range reflects finish tier and layout complexity within the interior conversion scope; the San Diego labor multiplier of 1.35× vs national median is baked in.