ADU guides, page 2
68 guides on what an ADU costs, what the law allows and how to hire well. Every number links to the state law, city page or study it came from.
Design
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, 2026
Plans
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, 2026
Prefab
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, 2026
Design
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, 2026
Basics
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, 2026
Design
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, 2026