Question 1

How many ADUs can I build in the City of San Diego?

Accepted Answer

A typical single-family lot can add one ADU inside existing space, one new attached or detached ADU, and one Junior ADU. Beyond that, San Diego's ADU Bonus Program allows additional units when you deed-restrict affordable ones, capped at 4 to 6 total units depending on lot size under the rules adopted in 2025. The bonus program has real strings attached, so it deserves a feasibility conversation, not a blog answer.

Question 2

Do I have to live on the property?

Accepted Answer

Not for a standard ADU. JADUs require the owner to live in the main home or the JADU. One wrinkle worth knowing: committing to live on site for three years earns any-size ADU a full impact fee exemption.

Question 3

How big can my ADU be?

Accepted Answer

New attached or detached ADUs can be up to 1,200 sq ft. Converting space that already exists, inside your house or an existing garage or accessory structure, has no size cap at all, and you can add up to 150 sq ft for entry and egress.

Question 4

Can I build a two-story ADU in San Diego?

Accepted Answer

Yes. The city allows detached ADUs up to two stories on single-family lots, subject to your zone's overall height limit. ADUs taller than 16 feet next to residential property need a 4-foot side and rear setback.

Question 5

What does state law guarantee me regardless of city rules?

Accepted Answer

California state ADU law sets the floor: cities must allow at least an 800 sq ft ADU with 4-foot side and rear setbacks and 16 feet of height on virtually any single-family lot.

Question 6

What setbacks apply to an ADU in San Diego?

Accepted Answer

This is where San Diego stands out: single-story ADUs at or under 16 feet can be built with zero side and rear setbacks in most of the city. In High or Very High Fire Hazard Severity Zones the minimum is 4 feet, and the fire official can require more. Front setbacks follow your base zone.

Question 7

Can I convert my garage into an ADU?

Accepted Answer

Yes, with no size cap, and the parking you lose generally does not have to be replaced. The exception is the Beach Impact Area near the coast, where parking rules still apply outside transit areas. We converted exactly this kind of garage in Bay Ho.

Question 8

What impact fees will I pay?

Accepted Answer

San Diego is more generous than state law requires: ADUs under 750 sq ft pay no development impact fees, and the first two ADUs on a property are exempt at any size. You still pay plan check, school fees, and a general plan maintenance fee, which is why our planning budgets carry a city fee allowance.

Question 9

Is parking required for a San Diego ADU?

Accepted Answer

Almost never. The citywide requirement is zero spaces. The exception is the coastal Beach Impact Area outside transit areas, and even there several waivers apply, including ADUs of 500 sq ft or less.

Question 10

How long does the permit take, and what about the coastal zone?

Accepted Answer

ADU permits are ministerial: staff review, no public hearing. Projects using preapproved plans get a 30-day review. Coastal properties can need a Coastal Development Permit and follow some older rules until state coastal certification catches up, so we confirm your parcel's status during feasibility.

ADU Regulations & Zoning in San Diego

Up to 3 ADUs plus a JADU on many single-family lots

Standard ADU

Detached ADU

Conversion ADU

JADU

What you can build in San Diego

How many ADUs can you build

Size and height

Setbacks and placement

Costs, parking, and process

Official San Diego resources

We don't just quote the rules. We build under them.

Bay Ho ADU in San Diego

North Park Bungalow ADU

Understanding ADUs: A Comprehensive Guide

How Can an ADU Make You Money?

Start your San Diego ADU the right way