Oct 9, 2026
How to Legalize an Unpermitted ADU in San Diego (AB 2533)
Built before 2020 without a permit? AB 2533 gives San Diego homeowners a clear path to legalize an unpermitted ADU or garage conversion. Here's how it works.
California's Premier Construction Management Agency
The Casita WayDesign. Bid. Build.
Casita manages your project from feasibility and design through permitting, competitive builder bidding, and construction.
One team and one point of contact for your ADU, from first sketch to keys. Based in San Diego, serving Southern California.
Casita ADU at a glance
Casita ADU is a construction management agency for accessory dwelling units (ADUs), based in Carlsbad in San Diego County, California. We design and permit your ADU, put the build out to competitive bid among licensed builders, and manage construction through final inspection, so you have one point of contact from first sketch to keys.
- Who it’s for
- Homeowners in San Diego County and across Southern California adding a detached ADU, attached ADU, garage conversion, or junior ADU (JADU), whether for rental income, family, or more space.
- What we do
- Feasibility, design, city permits, competitive builder bidding, and construction management. Casita ADU is not a general contractor: a licensed builder you select does the work, and we manage it for you.
- Where we work
- Every city in San Diego County, our home market, plus Orange County, Riverside County & the Inland Empire, Los Angeles County, and select California markets. Areas we serve
- How to reach us
- Call (619) 891-2065, email info@casitaadu.com, or book a free site walk. Office: 2100 Palomar Airport Rd, Suites 213 & 203, Carlsbad, CA 92011. Mon–Sat 8am–6pm · Sun closed.
Military Appreciation Program
Honoring Those Who Serve
To the men and women of our armed forces — thank you. Casita is proud to offer 15% off all ADU design costs for service members, veterans, and their families. From the first sketch to city-approved plans, it's our way of giving back to those who've given the most.
Who Qualifies
- Active Duty
- Veterans & Retirees
- Reserve & National Guard
- Military Spouses & Families
Just mention your service when booking — a military ID, DD-214, or VA card at your consultation is all we need.
15%
Off Design Costs
U.S. Military & Veterans
The Casita Way
Design. Bid. Build.
Casita is a construction management agency, not a builder. We design and permit your project, put it out to competitive bid among qualified licensed builders, then manage construction on your behalf. One team, one point of contact, no surprises.
1
Design
Feasibility, site walk, architectural design, engineering, and the complete permit package — submitted and shepherded through your city.
2
Bid
Qualified, licensed builders price the same set of plans. We compare the proposals with you line by line and coordinate the selection of your construction team.
3
Build
We manage your builder through construction — schedule, budget, inspections, and quality — all the way to final inspection and keys.
We also take on commercial projects and lot splits & SB9.
Same construction management team, same process.
Cost Estimator
What Will Your ADU Cost?
Configure your project and see live construction costs plus estimated permit fees for every jurisdiction in San Diego County — no email required.
San Diego County pricing.Building elsewhere in California? Book a consultation for market-specific numbers.
ADU type
Square footage750 sq ft
300 sq ft1,200 sq ft
Bedrooms
Bathrooms
Finish level
Site conditions
Costs and fees are calibrated for San Diego County. For Orange County, Riverside, Los Angeles, or elsewhere in California, book a consultation and we’ll price your market.
Estimated project cost
$187,000 – $249,500
$249–$333 per sq ft · typical timeline 9–13 months
Planning estimate, not a quote. Actual pricing depends on your site, plans, and finish selections — we’ll confirm real numbers after a site walk.
Construction Breakdown
Design & engineering$11,000 – $15,000
Site work & foundation$22,500 – $30,000
Framing & shell$30,000 – $40,000
Roofing & exterior$18,500 – $25,000
Windows & doors$9,500 – $12,500
Plumbing, electrical & HVAC$33,500 – $45,000
Insulation & drywall$13,000 – $17,500
Interior finishes & flooring$18,500 – $25,000
Kitchen$18,500 – $25,000
Bathroom(s)$11,000 – $15,000
Permits & Fees
City of San Diego
Plan check, permits & city fees$11,300 – $14,300
School district fees (~$5.17/sq ft)$3,900 – $3,900
Development impact fees (proportional, 750+ sq ft)$5,300 – $9,800
Water / sewer connection & capacity$3,500 – $9,000
Estimated total$24,000 – $37,000
Pre-approved plan programs can cut plan-check fees roughly in half.
Planning-level estimates from published 2025–2026 fee schedules and regional surveys. Impact fees are waived statewide under 750 sq ft; school fees don't apply at 500 sq ft or under. Always verify with your jurisdiction — a free Casita site walk turns these into real numbers for your parcel.
Get your full estimate report
We'll email this breakdown with permit details for your jurisdiction — and a Casita specialist will follow up about a free site walk.
No spam — just your estimate and a real human follow-up.
Our Process
How It Works
It starts with a free site walk. From there, four phases from dream to done.
1
Design
Feasibility, site walk, and custom or pre-approved plans sized to your lot and budget.
2
Permit
Complete permit package, city submittal, and plan-check responses — handled for you.
3
Bid
Competitive proposals from qualified licensed builders, compared side by side so you choose your construction team with confidence.
4
Build
Construction management of your selected builder through final inspection and keys.
Our Work
View All Projects Featured Projects
Keys day
See the project The Casita crew with homeowner Michael at his just-finished 1,034 sq ft detached ADU in Escondido.
“They rescued our ADU project. They were prompt, professional and have great follow through.”
Jennifer
Google review
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“We chose Casita, because they were personable, confident, and were really the first team we talked to who assured us that our project was doable with our budget.”
Heather
Google review
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“Winston is incredible to work with. He is attentive to details and made sure he was addressing any of the barriers that inevitably come up with most construction permitting processes and builds.”
Werner
Google review
About Winston, Founder & COO
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“I certainly appreciated the multiple site visits they made and frequent communications keeping me up to date. The interface with the contractor, the various subcontractors and the inspectors was all very smooth.”
S.
Google review
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“The cost was reasonable and presented up front. When we asked for some upgrades, it was written out first and we signed everything in advance. The cost was exactly what was quoted to us.”
Cherie
Google review
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“If you’re building an ADU and want someone who genuinely cares, knows their stuff, and won’t nickel and dime you — I highly recommend reaching out to Winston at Casita ADU.”
Mei
Google review
About Winston, Founder & COO
G
“…they did what they said they would do, without fail, on time … with a quality of workmanship that I did not expect.”
Marc
Google review
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“From beginning to end, the level of care, precision, communication, and workmanship was absolutely outstanding.”
Melissa
Google review
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In the News
Press & Announcements
PRLog
Why CASITA Chose Construction Management Over the Traditional ADU Contractor Model
The San Diego ADU company built its Design. Bid. Build. approach around transparency, competitive bidding and homeowner choice.
“We wanted homeowners to have an opportunity to understand the project before committing to who would build it.”
ADU Questions, Answered
Building an ADU in San Diego
Straight answers to the questions every San Diego homeowner asks before building an accessory dwelling unit.
Most San Diego County ADUs cost between $150,000 and $350,000 all-in. Garage conversions are the least expensive (often $150,000–$215,000), while a new detached 750 sq ft ADU with mid-range finishes typically runs $190,000–$250,000, plus roughly $10,000–$35,000 in permit, impact, school, and utility fees depending on your city and unit size. Casita's free online cost estimator gives you a live breakdown for your ADU type, size, finish level, and jurisdiction.
Plan on 9–13 months from first design meeting to move-in for a detached or attached ADU, and 6–10 months for a garage conversion. Design takes 4–8 weeks, city permitting 2–4 months (California requires cities to act on complete ADU applications within 60 days), and construction 4–6 months. Pre-approved plans can cut design and permitting time significantly.
Casita ADU is a construction management agency for accessory dwelling units — not a builder. The Casita Way is Design. Bid. Build.: we handle site feasibility, design, and city permits, put the project out to competitive bid among qualified licensed builders, then manage construction on your behalf through final inspection, so you have one point of contact from the first sketch to the keys. We are based in San Diego and serve every jurisdiction in San Diego County, plus Orange County, Riverside County and the Inland Empire, Los Angeles County, and select markets across California.
Almost certainly yes. California law (Gov. Code § 66314 and related statutes) requires every city to allow at least one ADU and one JADU on any residential lot with an existing or proposed single-family home, and cities cannot impose minimum lot sizes for ADUs. What varies by property is how big it can be, where it can sit, and whether utilities and access make it practical — which is exactly what a free Casita site walk answers.
No. Since January 1, 2025, California permanently prohibits cities from requiring owner-occupancy for ADUs (AB 976), so you can rent out both your home and the ADU. The one exception is a Junior ADU (JADU): the owner must live in either the main house or the JADU.
Yes — ADUs can be rented as long-term housing anywhere in California, and rental income is the most common reason San Diego homeowners build one. Short-term rentals under 30 days are regulated city by city (the City of San Diego, for example, requires a short-term residential occupancy license), so check local rules before planning an Airbnb.
Where We WorkBased in San Diego.
Based in San Diego.
Serving Southern California.
Casita designs, permits, bids, and manages construction of ADUs, garage conversions, and JADUs for homeowners throughout San Diego County — our home market — and now in Orange County, Riverside County and the Inland Empire, and Los Angeles County, with select projects elsewhere in California. Every city has its own ADU rules and fee schedule; we know San Diego's cold and do the homework everywhere else.
San Diego County
- San Diego, CA
- Carlsbad, CA
- Oceanside, CA
- Vista, CA
- Escondido, CA
- San Marcos, CA
- Encinitas, CA
- Chula Vista, CA
- El Cajon, CA
- La Mesa, CA
- Poway, CA
- Santee, CA
- National City, CA
- Coronado, CA
- Del Mar, CA
- Solana Beach, CA
- Imperial Beach, CA
- Lemon Grove, CA
- Unincorporated San Diego County
Southern California
In San Diego County? Run the free cost estimator — it prices permits for every jurisdiction above. Everywhere else, book a free consultation for market-specific pricing.
From the Blog
All Articles Latest Insights
Oct 2, 2026
New California ADU Laws for 2027: AB 956 and SB 1117 Signed
Newsom signed AB 956 and SB 1117 on Sept. 29. Here's what two detached ADUs per lot, lower impact fees, and AB 1815 mean for San Diego homeowners in 2027.
Sep 23, 2026
Building an ADU in a San Diego Fire Hazard Zone
San Diego's updated fire hazard maps put more lots inside mapped zones. Here's how that changes your ADU's materials, budget, and permit path.
Ready to Build Your Dream ADU?
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2100 Palomar Airport Rd, Suites 213 & 203, Carlsbad, CA 92011
Mon–Sat 8am–6pm · Sun closed