A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateADU Company in San Diego, CA
Adding an ADU, garage conversion, or home addition in San Diego means working with older wood-frame homes on small lots, many built between the 1920s and 1970s, often with outdated electrical panels and tight rear-yard access. Canyon-and-mesa terrain drives real variation in foundation and drainage costs that flatter cities never face. Seedling ADU San Diego handles all of it with a written price before work starts, background-checked crews, and the 365-Day Done Right Promise. Call (858) 988-6447 for a free estimate.
Why San Diego Homes Are Different
San Diego’s housing stock is dominated by 1920s – 1970s wood-frame bungalows, ranch styles, and Mira Mesa box tract homes on lots between 5,000 and 8,000 square feet. Many still run 100-amp electrical panels and cast-iron sewer laterals, so utility upgrades are a routine part of garage conversions and backyard ADUs. Rear-yard access is often limited to a narrow side gate, which changes how crews stage equipment and materials.
The bigger variable is topography. San Diego’s canyons and mesas mean plenty of single-family lots slope steeply or sit against environmentally sensitive edge zones. Excavation, retaining, and drainage engineering on a Clairemont hillside is a different job than the same square footage on a flat Chula Vista lot. Flat-roofed, stucco-clad ADUs tucked between the main house and the alley are common in North Park and City Heights, because setback and impervious-coverage rules push living space upward, not outward. Our crews plan for these conditions from the first site visit, and the written price reflects them before any tool is picked up.
Our Main San Diego Services
San Diego homeowners reach out to us most often for home additions, garage conversions, and detached ADUs. Each has its own San Diego page with local pricing, permit notes, and what to expect.
Home Addition Contractor in San Diego
A home addition in San Diego is often the more practical option when the existing house has the frame condition and lot width to extend outward. On smaller lots, a second-story addition can make more sense than pushing into the yard. San Diego’s Title 24 solar-ready and cool-roof rules come into play on nearly every addition, and older electrical panels usually need upgrading before drywall goes up. We handle the engineering, permitting, and the full build, with a crew that protects floors and keeps the work area clean at the end of each day. Learn more about our Home Addition Contractor in San Diego page, including local permitting specifics.
Garage Conversion Contractor in San Diego
Most San Diego garages built before the 1980s were never engineered as living space, so a conversion almost always involves new footings, slab work, insulation, and bringing the electrical panel up to code. Cast-iron sewer laterals are common, and tying a new bathroom into an aging line can mean trenching across the driveway. We price these realities upfront rather than discovering them mid-job. The Cedarwell Care Promise applies inside the house: shoe covers, drop cloths, and pet-safe products where there is a choice. See our Garage Conversion Contractor in San Diego page for full details.
ADU Builders in San Diego
A detached ADU on a San Diego lot is a new home on your property, built small and purposefully. Hillside lots often call for pier-and-beam foundations, and canyon-adjacent zones push us toward fire-resistant exterior materials. San Diego’s companion unit rules are relatively permissive compared with much of the state, but every project still needs a clear drainage plan and a separate subpanel. Ben Ortega and the Seedling team walk you through product choices without steering you toward whatever is easiest for us to build. Start with our ADU Builders in San Diego page.
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
You get an upfront price rangeHonest numbers before anyone is dispatched.
- 3
A background-checked tech heads outLicensed & insured, dispatched right away.
- 4
You approve before work beginsNothing starts until you say go.
Brands We Service in San Diego
We work hands-on with several brands serious ADU buyers research before calling anyone. Plant Prefab and Tuff Shed are common choices for San Diego lots, and James Hardie siding and trim materials hold up well to intense sun and Santa Ana wind seasons. See all our brands and how we help you choose what fits your lot and budget.
Pricing for ADU Company in San Diego, CA
The ranges below reflect what San Diego homeowners typically see on written estimates for this type of work. Canyon lots, old panels, and sewer line replacements move a project toward the upper end.
| Service | Typical range in San Diego |
|---|---|
| Detached ADU (prefab or panelized) | $180,000 – $350,000 |
| Detached ADU (stick-built, hillside lot) | $250,000 – $450,000 |
| Garage conversion to ADU (studio, attached garage) | $120,000 – $200,000 |
| Garage conversion to ADU (with bathroom and kitchen) | $180,000 – $280,000 |
| Home addition (single room, 300 – 500 sq ft) | $80,000 – $160,000 |
| Home addition (primary suite, 500 – 800 sq ft) | $150,000 – $280,000 |
| Second-story addition (partial, over existing footprint) | $200,000 – $400,000 |
| Electrical panel upgrade (100A to 200A) | $3,500 – $6,500 |
| Sewer lateral replacement (cast-iron to PVC) | $6,000 – $15,000 |
| Site prep and drainage on sloped lot | $10,000 – $40,000 |
What pushes price up in San Diego more than anything is the slope. A rear-yard ADU on a Tierrasanta hillside can need retaining, pier drilling, and engineered drainage before framing starts. The second variable is utility work: a 60-year-old panel and a cast-iron sewer line are quiet five-figure additions that cheap estimates leave out. Every Seedling San Diego quote is a written price before work begins, and no line items get added after crews arrive.
Neighborhoods We Serve in San Diego
We work across San Diego, from coastal mesas to canyon-adjacent tracts. Response time for an initial site visit is typically within a few business days across the metro area.
- Clairemont
- North Park
- City Heights
- Mira Mesa
- Tierrasanta
Service Area – Cities Near San Diego
Our San Diego office also schedules work in neighboring communities. If you’re in Coronado, CA, National City, CA, Chula Vista, CA, or Lemon Grove, CA, the same written-price promise and Cedarwell Care Promise apply. Call for a free estimate and we’ll confirm coverage for your address.
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 Company in San Diego
After you approve a written estimate, we typically begin design and permitting within two to three weeks. San Diego permit timelines vary by neighborhood and project type. Call (858) 988-6447 and we’ll give you an honest schedule for your specific lot.
Many San Diego HOAs still require architectural review even though state law limits their ability to block ADUs outright. We prepare the drawings and documents your board will request. Call (858) 988-6447 to talk through your HOA’s specific rules.
We serve the full San Diego metro area, including canyon-adjacent lots and neighborhoods with tight alley access. If your property is outside the immediate San Diego area, ask us during the estimate call and we’ll confirm coverage.
What happens when you call
- 1A real person answersNo phone trees - talk to a local adu pro.
- 2You get an upfront price rangeHonest numbers before anyone is dispatched. No surprises.
- 3We come out and measureLicensed & insured, at a time that suits you - the visit and the quote are both free.
- 4You get the price in writingLine-itemed, yours to keep, and nothing starts until you say go.
What San Diego Customers Say
"Built a backyard unit for us. For a months long project the crew kept the site remarkably tidy, swept daily, and were respectful of our neighbors and our dog. Beautiful result."
- Charlotte Vey"They converted our garage and were so mindful that we were living right there through it. Quiet hours respected, site swept, nothing left out where the kids play. Lovely work."
- Eugene Park"Junior ADU conversion inside the house. They were incredibly clean about it, plastic walls, floor protection, daily cleanup, all with a toddler in the home. Couldn't have asked for more care."
- Marcus Oyelaran
