ADU Planning Guide
San Diego ADU Floor Plans,
Types & Size Guide
Everything you need to understand your ADU options in San Diego County — sizes, types, timelines, and how to choose what's right for your property.
By Square Footage
ADU sizes in San Diego
Most San Diego County jurisdictions allow ADUs up to 1,200 sqft. The size you choose affects fees, permits, and rental potential.
Compact
400–500 sqft
JADU / Studio
Home office, aging parent, first rental
Typical timeline
3–5 months
1-Bedroom
600 sqft
Detached ADU
Long-term rental, guest suite, in-law unit
Typical timeline
6–9 months
1–2 Bedroom
800 sqft
Detached ADU
Strong rental income, multi-gen living
Typical timeline
7–10 months
2+ Bedroom
1,000+ sqft
Detached ADU
Maximum rental income, long-term hold
Typical timeline
10–14 months
By Type
The four ADU types in San Diego
Detached ADU
A standalone structure in your backyard. Most privacy for both tenant and homeowner. Highest resale value. Typical size: 400–1,200 sqft.
Attached ADU
Built as an addition sharing at least one wall with your primary home. More affordable than detached. Good for tight lots.
Garage Conversion
Converts an existing attached or detached garage into a full living unit. Most affordable option. Fastest permit timeline.
Junior ADU (JADU)
Up to 500 sqft within your existing home's footprint. Often a converted bedroom or suite. Exempt from most impact fees.
The Smart Path
San Diego pre-approved plan program
San Diego, Encinitas, Carlsbad, Del Mar, and San Marcos all have libraries of pre-engineered ADU plans that have already cleared structural review. Pick one, site-adapt it, and skip the longest part of permitting. Most homeowners save $30–50K and 3–4 months.
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