ADU guides, with sources
What it costs, what the law allows and how to hire well. Every number links to the state law, city page or study it came from.
Cost
What an ADU costs in San Diego
All-in prices by ADU type, city fees by size, the site costs that surprise people and how to pay for it.
Read the guide
Rules
California ADU laws in 2026, in plain English
How many units you can build, size and setback limits, the 60-day permit clock, parking, rentals and fees.
Updated Oct 26, 2026
Hiring
How to hire an ADU contractor in California
The license to look for, what the contract must say, deposit limits and how to avoid liens.
Updated Oct 26, 2026
Basics
What is an ADU? Types, uses and the San Diego process
Detached, attached, conversion and junior ADUs, who issues your permit, and how long a project takes.
Updated Oct 26, 2026
Conversions
Garage conversion ADU in San Diego: permits, cost and rules
Why no parking or setbacks apply, the code upgrades a garage needs, the permit, costs, and convert vs. rebuild.
Updated Oct 26, 2026
Permits
How to get an ADU permit in San Diego (2026)
Who issues it, what to submit, the 60-day review clock, city fees, coastal and fire zones, and inspections.
Updated Oct 26, 2026Junior ADU
Junior ADU (JADU) rules in California and San Diego
The 500 sq ft limit, efficiency kitchen, owner occupancy after AB 1154, renting, fees, cost and how a JADU compares to an ADU.
Updated Oct 26, 2026ADU types
Attached vs detached ADU: cost, rules and which to build
Size and height limits, setbacks, fire walls, solar, cost ranges and San Diego rules for attached and detached ADUs.
Updated Oct 26, 2026Financing
ADU financing: how to pay for an ADU in California
HELOCs, cash-out refis, renovation and construction loans compared, how lenders count ADU rent, and how to protect loan draws.
Updated Oct 26, 2026Grants
ADU grants in California (2026): what's still available
Which ADU grants and loans are open or closed, San Diego programs, fee exemptions worth more than a grant, and grant scams.
Updated Oct 26, 2026Renting
ADU rental income in San Diego: rents, rules and payback
What ADUs rent for, how long one takes to pay back, the 31-day minimum, AB 1482 tenant rules, Section 8 and taxes.
Updated Oct 26, 2026
Real estate
What is an ADU in real estate? Value, appraisals and selling
What ADU means, how appraisers and lenders treat one, whether it adds value, property tax, disclosure and selling it as a condo.
Updated Oct 26, 2026Design
ADU floor plans and sizes: what fits in 400 to 1,200 square feet
What fits at each ADU size, from a studio to three bedrooms, the size lines that cut fees, and free plans to download.
Updated Oct 26, 2026Plans
Pre-approved ADU plans in San Diego: free plans and the 30-day review
Which local programs exist, which plans are free, what the City of San Diego accepts, and what pre-approval doesn't cover.
Updated Oct 26, 2026Prefab
Prefab ADUs in California: costs, approvals and what's included
Modular, manufactured, kit and tiny-home units, who approves what, the license to look for and the true all-in cost.
Updated Oct 26, 2026Design
Two-story ADUs in California and San Diego: height rules and costs
State height minimums, San Diego's two-story and setback rules, ADUs over garages, the coastal height limit and cost examples.
Updated Oct 26, 2026
Cost
ADU construction cost in California: price per square foot by size
2026 builder prices by size and region, where the money goes, fees, why small units cost more per foot and how to save.
Updated Oct 26, 2026Basics
Granny flat vs ADU: what a granny flat is in California
Granny flat, in-law unit, casita: what the names mean legally, the rules for family and seniors, design for aging in place and costs.
Updated Oct 26, 2026Basics
Granny pod: what it is, what it costs and whether it's legal in California
Granny pods explained: when one counts as an ADU, pods on wheels, permits, 2026 prices, accessible design and what to check before you buy.
Updated Oct 26, 2026Basics
Mother-in-law suite in California: rules, options and cost
Bedroom suite, junior ADU, attached or detached ADU: where the legal line falls, permits, San Diego rules, costs and buying a home with one.
Updated Oct 26, 2026Cost
Garage conversion cost in San Diego and California (2026)
What a garage conversion costs as an ADU or a bedroom, line by line, one-car vs. two-car, fees and ways to save.
Updated Oct 26, 2026Rules
How to convert a garage to living space in California
Bedroom or office vs. ADU: permits, ceiling and egress code, San Diego's parking rules and the risks of skipping the permit.
Updated Oct 26, 2026Basics
Guest house vs ADU in California: what's allowed and what it costs
Guest quarters vs ADU: San Diego's no-kitchen rule, size and rental limits, permits, 2026 costs and how to turn a guest house into a legal ADU.
Updated Oct 26, 2026Design
Pool house or ADU? California rules for building by the pool
Cabana, guest quarters or ADU: shower and kitchen limits, converting with no new setbacks, utilities, rentals, pool safety rules and costs.
Updated Oct 26, 2026Design
Carriage house ADU: building an apartment above a garage in California
What a carriage house is, when a garage apartment counts as an ADU, San Diego height and setback rules, fire separation, stairs and costs.
Updated Oct 26, 2026Real estate
Homes with ADUs: what to check before you buy in California
How to check an ADU's permit, what the seller must disclose, unpermitted units, loans and rent, tenants, an inspection checklist and property tax.
Updated Oct 26, 2026Prefab
Tiny home ADU in California: when a backyard tiny home is legal
When a tiny home counts as an ADU, tiny homes on wheels, San Diego's movable tiny house rules, permits, utilities and cost.
Updated Oct 26, 2026Prefab
Amazon tiny home or Home Depot kit: can it be a legal ADU in California?
What online tiny home kits really are, why many aren't permit-ready, how to permit one, real costs and safer alternatives.
Updated Oct 26, 2026