ADU Contractors in San Diego: Find the Right Builder for Your Project
Building an ADU in San Diego is one of the better financial decisions a homeowner can make right now. Rental demand across the county is strong, the state has made permitting easier than it’s been in decades, and property values in most San Diego neighborhoods mean that a well-built ADU adds real, measurable equity to your home. The challenge most homeowners run into has nothing to do with whether to build one. It’s figuring out who to hire to build it.
That part is harder than it sounds. ADU construction in San Diego involves a specific set of permits, city requirements, and construction phases that not every contractor handles regularly. Hiring someone who has built a handful of ADUs is a different experience from hiring someone who builds them consistently across San Diego County and knows exactly what each city’s building department expects. The gap between those two contractors shows up in your timeline, your budget, and your stress level.
This page covers what San Diego homeowners need to know before starting an ADU project, costs, permits, what to look for in a contractor, and how Build Wize takes the search off your plate entirely.
What Is an ADU and What Can You Build in San Diego?
An ADU, accessory dwelling unit, is a secondary living space on your existing residential property. In San Diego that typically means one of four things: a detached backyard cottage, a garage conversion, an attached addition to your existing home, or a junior ADU carved out of existing interior space.
California law has changed significantly in recent years to make ADU construction easier for homeowners. San Diego has adopted these state rules, which means reduced setback requirements, streamlined permit review for certain ADU types, and the elimination of some of the older parking replacement requirements that used to make garage conversions complicated.
What you can build depends on your lot size, your existing home’s square footage, your zoning designation, and whether you’re in a coastal zone or a historic district. A contractor who builds ADUs in San Diego regularly will assess all of this in the first conversation. One who doesn’t will figure it out as they go, which costs you time and money.
ADU Costs in San Diego: What Homeowners Are Actually Spending
ADU costs in San Diego vary more than most contractors will tell you upfront. Here’s what the numbers actually look like across different project types:
Detached ADU (new construction): $180,000 to $350,000 for most projects. A basic 400 to 600 square foot unit with standard finishes sits at the lower end. A larger unit with higher-end finishes, a full kitchen, and separate utility connections climbs toward $300,000 and beyond.
Garage conversion ADU: $80,000 to $150,000. The existing structure reduces costs significantly, but electrical upgrades, insulation, HVAC, plumbing for a bathroom and kitchen, and permit fees add up faster than most homeowners expect.
Junior ADU (JADU): $40,000 to $80,000. These are carved out of existing interior space, typically a bedroom suite with a separate entrance and a kitchenette. Lower cost, but limited to 500 square feet under California law.
Attached ADU: $120,000 to $220,000 depending on size and how much structural work the attachment requires.
Permit fees in San Diego City and surrounding municipalities add $10,000 to $25,000 on top of construction costs for a detached ADU, depending on the size and complexity of the project. Some contractors include permit fees in their quotes. Others list them separately. Always ask which one you’re looking at before comparing bids.
If you’re ready to get real quotes from ADU contractors who build regularly in San Diego, tell us about your project and we’ll match you with the right ones at no cost to you.
ADU Permits in San Diego: The Honest Timeline
This is where most ADU projects lose months before a single shovel hits the ground. Understanding the permit process upfront saves you from the frustration of expecting a 6-month build and getting a 14-month experience instead.
Design and plans: 4 to 10 weeks depending on the complexity of the project and how quickly your designer or architect works. Some contractors have in-house designers. Others work with preferred architects they’ve used before, which tends to move faster than starting from scratch.
Permit submission and review: San Diego City’s Building and Development Services department typically takes 6 to 12 weeks for initial ADU permit review. Corrections are common — if the department sends back a correction letter, that adds another round of revisions and re-review, which can add 4 to 8 weeks.
Construction: Once permits are in hand, construction on a detached ADU typically runs 4 to 8 months. Garage conversions can move faster, sometimes completing in 3 to 5 months.
Total realistic timeline from the day you decide to build to the day someone moves in: 10 to 18 months. That’s not a worst-case scenario. That’s the common experience for San Diego homeowners who didn’t anticipate permitting delays.
A contractor who quotes you a 6-month timeline without accounting for permitting is either not including that phase in their estimate or is being optimistic in a way that won’t serve you well. Our process at Build Wize is explained in detail on our How It Works page, we match you with ADU contractors who give you honest timelines from the first conversation, not the ones you want to hear.
Is an ADU Worth It in San Diego?
For most homeowners in San Diego County, yes. The math works in most neighborhoods.
Rental rates for a one-bedroom ADU in San Diego currently range from $1,600 in areas like El Cajon and Spring Valley to $2,800 or more in La Jolla, Encinitas, and coastal communities. At $2,000 per month, a $220,000 ADU investment generates $24,000 per year in gross rental income. That’s roughly a 9-year payback period on the construction cost alone and you still own a property that’s worth more than when you started.
The return gets better if you’re in a high-demand rental area, if you plan to use the ADU for a family member rather than paying for separate housing, or if the ADU pushes your property into a higher value bracket for a future sale.
It gets worse if construction runs significantly over budget, if permitting delays push your rental income start date by 6 months, or if you hire a contractor who cuts corners and leaves you with work that doesn’t pass final inspection. All three of those outcomes are more common than they should be and all three are more likely when homeowners hire a contractor without properly vetting their ADU experience.
What to Look for in a San Diego ADU Contractor
Not every licensed general contractor is the right fit for an ADU project. General construction experience and ADU-specific experience are different things. Here’s what to ask any contractor you’re considering:
How many ADUs have you completed in San Diego County? Ask for a specific number. Ask which cities. Permit requirements differ between San Diego City, Chula Vista, El Cajon, and Escondido. A contractor who has only built in one jurisdiction may not know the specific expectations of another.
Can you handle the full scope or do you subcontract design? Some contractors manage the entire process including design, permitting, and construction. Others handle construction only and expect you to arrive with approved plans. Know which one you’re hiring before you sign anything.
What does your permit process look like? A contractor who has done this many times will walk you through their permitting timeline with confidence. One who is vague about it is either new to ADU construction or accustomed to homeowners not asking.
What does your payment schedule look like? California law caps deposits at 10% of the total project cost or $1,000, whichever is less. Progress payments tied to completed milestones are standard. A large payment before work begins is not.
Do you have references from recent ADU projects? Ask for two or three. Call them. Ask how the project went, whether it came in on budget, and whether they would hire the contractor again.
At Build Wize we only work with ADU contractors who have verified experience in San Diego County. We check their CSLB license, their insurance, their BBB standing, and we review their past projects before they ever get matched with a homeowner. You don’t have to run through this checklist on your own.
How Build Wize Helps San Diego Homeowners Find ADU Contractors
Finding an ADU contractor in San Diego without help looks like this: you Google a few names, you call four or five companies, two don’t call back, one comes out to look at your yard and then goes quiet for two weeks, and you’re no closer to starting than when you began.
Build Wize cuts that process down to a single form. You tell us your project, ADU type, approximate size, location, and timeline and within 24 hours we personally match you with up to 3 ADU contractors from our vetted network who are the right fit for your specific project. They contact you directly and come to your property for a free consultation. You meet them, ask your questions, compare their quotes, and choose the one you want to work with.
There’s no fee for homeowners at any stage. We earn a referral fee from the contractor only after your project is completed. Your only job is to describe your project and show up for the consultations.
FAQ: San Diego ADU Questions
Q. Do I need a permit for an ADU in San Diego?
A. Yes, always. Any ADU detached, attached, or garage conversion requires building permits in San Diego. Working without permits creates serious problems at resale and can result in the city requiring you to remove unpermitted work at your own expense.
Q. Can I build an ADU on any residential lot in San Diego?
A. Most single-family residential lots in San Diego qualify for at least one ADU. Some lots qualify for both a full ADU and a junior ADU. Lot size, zoning, and existing structures affect what’s possible. An experienced ADU contractor will assess your specific property in the initial consultation.
Q. How much does a garage conversion ADU cost in San Diego?
A. Most garage conversions in San Diego run $80,000 to $150,000. The main cost drivers are plumbing for a bathroom and kitchen, electrical upgrades, insulation, HVAC, windows, and finishes. Permit fees add $5,000 to $15,000 on top of construction costs.
Q. Are ADU builders licensed and insured?
A. Every contractor in our network is verified for licensing and insurance.
Q. Can Build Wize match me with ground-up construction contractors?
A. Yes. We work with contractors specializing in full new construction projects.
Q. Will an ADU affect my property taxes?
A. Yes, but only on the value of the ADU itself, not your entire property. California’s Proposition 13 protects your existing assessed value. The ADU is assessed separately as new construction and added to your tax bill.
Q. Can I build an ADU for rental income?
A. Yes. Many contractors specialize in income-producing ADUs.
Q. Are permits handled by the contractor?
A. Yes. The contractors we match you with manage permits and inspections when required.
Q. How do I get matched with an ADU contractor through Build Wize?
A. Fill out the short form on our contact page. It takes about 90 seconds. Tell us your ADU type, your location in San Diego County, your rough timeline, and your budget range. We review it personally and come back to you within 24 hours with your contractor matches. No cost, no obligation.
Q. Can Build Wize help with ADUs outside San Diego City?
A. Yes. We serve all of San Diego County including Chula Vista, El Cajon, La Mesa, Santee, Escondido, Oceanside, Carlsbad, Encinitas, and surrounding areas.
Contact Us
Address
9655 Granite Ridge Dr, San Diego, CA 92123
Office Time
Mon-Thurs: 8:30am – 6:00pm
Friday: 8:00am – 12:00pm
Saturday & Sunday: Closed
Contact Us
Address
9655 Granite Ridge Dr, San Diego, CA 92123
Office Time
Mon-Thurs: 8:30am – 6:00pm
Friday: 8:00am – 12:00pm
Saturday & Sunday: Closed