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ADU construction in Torrance typically costs between $90,000 and $220,000 for a complete unit in 2026. A standard one-bedroom, one-bathroom detached ADU in neighborhoods like Old Torrance or Southwood generally lands between $120,000 and $160,000, while a larger two-bedroom unit or a garage conversion with extensive foundation work can push toward the top of that range. Your actual price will depend mostly on size, how the unit attaches to your property, and what level of finish you choose.
ADU Construction Cost Breakdown (2026)
Here’s where the money goes on a typical Torrance ADU project. These are real working numbers from the local market, not national averages.
| Line Item | Typical Cost Range (Torrance, 2026) |
|---|---|
| Design & architectural plans | $8,000 – $20,000 |
| Permits & city fees (Torrance) | $6,000 – $15,000 |
| Site prep & foundation | $15,000 – $35,000 |
| Framing & roofing | $20,000 – $45,000 |
| Plumbing & electrical rough-in | $12,000 – $28,000 |
| HVAC (mini-split or tie-in) | $4,000 – $12,000 |
| Drywall, insulation & paint | $8,000 – $18,000 |
| Flooring | $3,000 – $9,000 |
| Kitchenette (cabinets, counters, appliances) | $6,000 – $18,000 |
| Bathroom (fixtures, tile, shower) | $7,000 – $20,000 |
| Exterior finish & landscaping | $4,000 – $12,000 |
What pushes a project toward the bottom of that range? A smaller footprint under 500 square feet, a conversion of existing space like a garage with solid slab already poured, and budget-conscious finishes from national brands. What pushes it toward the top? A detached two-bedroom unit with custom kitchen cabinets, premium flooring, upgraded electrical panel work, and a new concrete foundation on a sloping lot.
One thing Torrance homeowners don’t always anticipate: the city’s utility connection fees. Connecting a new ADU to water and sewer lines can run thousands of dollars depending on how far your unit sits from the main lines. We see this surprise homeowners regularly in the Seaside and Walteria areas where lots are deeper than they appear from the street. A good contractor includes these fees in the written price up front. Ours does, every time.
What Affects ADU Construction Pricing in Torrance
Not every ADU costs the same, even at the same square footage. Here are the six factors that move the number most in this city.
- Attached vs. detached vs. conversion. A garage conversion in Torrance typically runs $30,000 to $80,000 because the structure already exists. A detached ADU with new foundation, new utility trenching, and full exterior finish runs significantly more. Attached additions fall in between.
- Soil and foundation conditions. Parts of Torrance, especially neighborhoods south of Sepulveda near the coast, sit on soil that requires deeper footings or additional compaction. This is one of those costs that shows up as a line item and can range from $5,000 to $20,000 depending on what’s under your lot.
- Utility connection distance. If your ADU goes in the back corner of a deep Walteria lot, running sewer, water, and electrical lines adds real money. Trenching through existing landscaping or concrete also adds cost and time.
- Finishes and fixtures. A kitchenette with stock cabinetry and laminate counters costs a fraction of one with KraftMaid cabinetry, Caesarstone surfaces, and Kohler fixtures. The gap between builder-grade and specification-grade finishes on an ADU can be $15,000 to $40,000 all by itself.
- City of Torrance requirements. Torrance enforces specific setback rules, parking requirements in certain zones, and design standards for ADUs in historic or hillside overlay areas. Some neighborhoods, particularly in the Hillside Overlay District, trigger additional engineering review that adds to plan costs.
- Panel and electrical capacity. A new ADU often means a new subpanel or a full main panel upgrade. If your Torrance home still runs an older 100-amp panel, plan for $2,500 to $6,000 in electrical work before the ADU even gets wired.
How to Save on ADU Construction
Saving money on an ADU doesn’t mean cutting corners. It means making smart decisions early, before plans are even drawn. The biggest savings come from choices you make in the first two weeks of planning.
- Convert instead of building new. If you have an attached or detached garage, converting it typically saves $40,000 to $80,000 versus a ground-up detached unit. The slab, framing, and roof are already there.
- Keep the footprint simple. A rectangle with a simple gable roof costs less to frame, roof, and insulate than an L-shaped plan with hips and valleys. Every corner adds labor and material.
- Choose stock sizes and standard materials. Custom window sizes, unusual door heights, and specialty tile create waste and labor cost. Standard sizes install faster, and faster installation means lower labor bills.
- Bundle the project with other work. If you’re planning a main house remodel alongside the ADU, doing both at once reduces mobilization costs and lets trades work across both projects. The savings can be 5 to 10 percent of total cost.
- Get a written price before you commit. The single most effective way to control ADU cost is to work with a contractor who puts the entire price in writing before work begins. No verbal estimate that grows. No change orders that appear out of nowhere. Our process at Mason Remodeling includes a written price on every ADU project, delivered before any tools are unpacked. If you want to compare that against other bids, call (424) 337-6939 for a free estimate.
FAQs – ADU Construction Cost
Is it cheaper to build an ADU or convert a garage in Torrance?
Converting a garage is significantly cheaper, typically $30,000 to $80,000 in Torrance, compared to $90,000 to $220,000 for a new detached ADU. The savings come from reusing the existing structure, slab, and often the roofline. Call (424) 337-6939 and we’ll look at your garage’s specific condition and tell you which path makes sense for your lot.
How much does a 500 square foot ADU cost in Torrance?
A 500-square-foot ADU in Torrance typically costs $110,000 to $190,000 depending on whether it’s attached, detached, or a conversion, and what level of finish you choose. Smaller units often have higher cost per square foot because fixed costs like permits and utility connections don’t shrink with size.
Can you build an ADU for under $100,000 in Torrance?
Yes, but usually only as a garage conversion or a very small attached unit with builder-grade finishes. A detached unit under $100,000 in Torrance is rare in 2026 given current permit fees, labor rates, and material costs. Call (424) 337-6939 and we’ll give you an honest read on what your specific property can achieve within your budget.
How long does ADU construction take in Torrance?
Plan for 9 to 14 months from initial design to move-in for a detached ADU in Torrance. City plan review typically takes 4 to 8 weeks, and construction itself runs 5 to 8 months depending on complexity and weather windows. Garage conversions move faster, often 4 to 7 months total.
Do I need a permit to build an ADU in Torrance?
Yes, every ADU in Torrance requires city permits, including garage conversions and pre-fabricated units. The permit and fee line item on a Torrance ADU typically runs $6,000 to $15,000 depending on the scope and any utility connection fees. A reputable contractor handles this paperwork for you. We do.
What’s the most expensive part of building an ADU?
Foundation and utility work is consistently the most expensive and least predictable line item on Torrance ADU projects, ranging from $15,000 to $35,000 or more for site prep, concrete, and trenching. This is also where surprise costs appear on lots with poor soil, deep utility lines, or difficult access. That’s why we price ADUs with a written number that accounts for these conditions before we start.
If you’re considering an ADU on your Torrance property, start with a real number. Our team at Mason Remodeling Co Torrance has been building in this city since 2004, and we walk every property before we price it. You’ll get a written price before any work starts, a crew you know by name and photo before they arrive, and a 365-Day Done Right Promise on every completed project. Call (424) 337-6939 for a free ADU estimate. A live person answers, day or night.
Pricing reflects the Torrance market as of 2026. Mason Remodeling Co Torrance offers free estimates – call (424) 337-6939.
Written by Isaac Pruett, Owner at Mason Remodeling Co Torrance, serving Torrance since 2004.
What Our Customers Say
"Basement refinish with egress window. Drywall finish is smooth and the electrician was tidy."
- Kyle S."Opened up the wall between kitchen and dining room. They handled the beam and permit and the floor transitions look seamless."
- Wendy A."Good work on the hall bath. They found a rotted subfloor, which added cost, but showed me photos and a clear price first."
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