A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateFast, Reliable ADU Builders Across San Diego
Most San Diego ADU projects can be permitted and built within 7 to 14 months, depending on lot conditions and whether you’re using a prefab platform or conventional framing. Our crews work across San Diego County every week, from Allied Gardens to San Carlos to Clairemont. If you’re planning a detached unit, a garage conversion, or a Junior ADU, call (858) 264-3027 and we’ll walk you through what your specific lot will actually require before you spend a dollar on plans.
We know the difference between a city permit in Ocean Beach and a county permit on an unsewered lot east of the 15. That local knowledge changes the bid, the schedule, and sometimes the entire site plan. You don’t need a builder who’s learning San Diego rules on your dime. You need someone who already knows them.
Why Fielding ADU San Diego Is San Diego’s Preferred ADU Builders Company
Fielding ADU Builders operates inside the Garrison Partners family, an independent local business that has held itself to The Garrison Standard since 2006. That standard is not a marketing line. It means a written price before any work starts, permits pulled by the book, a background-checked uniformed crew on site, and a written one-year guarantee on every project.
Reed Calloway leads our San Diego operation. Homeowners across the county call us after a previous contractor missed the schedule, moved the number mid-job, or left the permit board empty. We hear it often enough that our whole process is built to answer that history: price in writing on day one, a schedule you can hold us to, and a final invoice that matches the approved number.
Every call to (858) 264-3027 is answered by a live person. No voicemail tree. No callback queue. If you call at noon or midnight, someone picks up. That matters when a county inspector flags a setback and you need an answer before the crew stops work.
ADU Contractor in San Diego
An ADU Contractor in San Diego handles the full build: site prep, foundation, framing or modular set, rough and finish mechanicals, and final inspection coordination. On San Diego’s larger post-WWII lots, the contractor’s first job is often figuring out where the unit can legally sit given setbacks, easements, slope, and any septic or well constraints.
Site Scoping Before the Bid
On unsewered lots in east San Diego, county health rules govern septic system setbacks, not city sewer standards. We check those before we quote. A 750 sq ft ADU that looks simple on paper can require a septic variance and a compact excavator to cut a 120-foot utility trench without disturbing mature trees. That’s real scope, and it belongs in the written price, not as a change order later.
Foundation and Utility Planning
Many San Diego ranch homes from the 1960s and 1970s sit on raised foundations. That can simplify tying a new ADU into existing utility lines, but it also means planning for a new concrete slab with proper drainage on the open lot. We bid that work explicitly so you’re not surprised when equipment shows up.
ADU Design in San Diego
ADU Design in San Diego starts with the lot, not the floor plan. A flat Clairemont parcel and a sloped San Carlos acreage lot produce different designs, different foundation requirements, and different costs. We design backwards from what your specific parcel allows under current San Diego code and the Bonus ADU program.
Designing for the Two-Tier Market
San Diego’s Bonus ADU program lets a homeowner build two ADUs on one lot if one is deed-restricted affordable. That reshapes the design conversation. A high-end coastal-style unit with a rooftop deck in Ocean Beach rents differently than a modest second unit inland. We design for the rental reality in your specific neighborhood, not a generic California floor plan.
Materials That Match the Lot
On a recent San Carlos project, we specified James Hardie fiber-cement siding to match the existing 1960s ranch. The design also accounted for wildfire zone requirements in the eastern part of the city, where ember-resistant assemblies are not optional. Those choices belong in the design phase, before plan-check, not after a correction letter.
Trusted Brands We Service in San Diego
We work daily with the prefab and modular platforms San Diego homeowners are already researching: Boxabl, Plant Prefab, and Abodu among others. For conventional builds, we regularly spec James Hardie siding and Tuff Shed-style structures where the budget calls for a simpler shell. Our crews are fluent in the set requirements, utility tie-ins, and inspection sequences for each platform. That means faster plan-check approval and fewer surprises on delivery day.
Common ADU Builders Problems We See in San Diego Homes
- Ignoring the Bonus ADU economics. Building a high-end unit with a rooftop deck in an inland neighborhood like Clairemont, then watching it sit vacant at the projected rent. San Diego’s two-tier market rewards designs matched to the exact submarket.
- Septic and well setbacks on rural lots. On unsewered east San Diego parcels, builders sometimes order materials before county health approval. We’ve seen demo costs eaten because the septic setback was never cleared first.
- Wildfire zone material errors. Standard insulation and single-pane windows get flagged in San Diego’s eastern wildfire-prone areas. Non-compliant ember-resistant assemblies trigger costly plan-check corrections that a competent designer never triggers in the first place.
- Coastal height and setback surprises. In Ocean Beach and Pacific Beach, small lots and coastal height limits create narrow buildable envelopes. A design that works in San Carlos will not necessarily work three blocks from the water.
Pricing for ADU Builders in San Diego, CA
In San Diego, a garage conversion typically runs $120,000 to $180,000 before permit fees. A new detached ADU from 500 to 750 sq ft generally lands between $220,000 and $350,000. A Junior ADU carved from existing interior space often comes in at $80,000 to $140,000.
What moves the number on acreage lots: septic system work, long utility trenches, grading and drainage on open soil, and fire-resistant material upgrades. We price all of that in writing before work begins. Call (858) 264-3027 for a free estimate, and you’ll get a real number tied to your actual parcel, not a ballpark you can’t hold anyone to.
We Also Serve Cities Near San Diego
Our crews serve San Diego and the surrounding communities including Coronado, National City, Lemon Grove, and Bonita. If you’re unsure whether your lot falls under city or county jurisdiction, call (858) 264-3027 and we’ll check. You can also read more about our full capability as ADU Builders or see how we work throughout San Diego.
Serving San Diego, CA - Our Local Coverage Area
We’re based in the San Diego area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs About ADU Builders in San Diego
Yes, if one of the two units is deed-restricted affordable at an income level the city specifies, San Diego allows a second market-rate ADU on the same lot. This is unique among neighboring cities and changes the financial model for owners with larger post-WWII parcels in areas like San Carlos or Allied Gardens. Call (858) 264-3027 and we’ll evaluate whether your lot qualifies.
They do. On unsewered lots, county health setback rules govern how close an ADU can sit to a septic tank, leach field, or well. Those setbacks are often more restrictive than city sewer standards and can dictate the entire site plan. We check county health approval before ordering a single material.
If your property sits within a half-mile of a transit stop, a 2020 state law largely eliminates parking requirements for ADUs. That can save $15,000 to $40,000 in grading, paving, and paving-related drainage work depending on the lot. We verify your transit proximity during the free estimate, because it directly changes the bid.
An alley flat is a second unit facing the rear alley rather than the street, built behind the original bungalow. Dense lots and coastal height limits make these common in Ocean Beach and Pacific Beach, often with a rooftop deck to capture ocean breezes. The design is specific to the parcel width and alley access, and it costs differently than a standard backyard unit.
Yes. In the eastern and northern wildfire-prone areas of the city, plan-check will require ember-resistant vents, tempered glass, and fire-rated siding assemblies. Specifying those materials from the start keeps your permit review from stalling. Call (858) 264-3027 for a detailed quote that accounts for your zone.
Written by Reed Calloway, Owner at Fielding ADU San Diego, building to The Garrison Standard since 2006.
