Skip to content
Renovated Cabrillo Bungalows cottage by DECOMA Industries, near Harbor City in San Pedro

Residential

Harbor City ADU contractor.

Looking for an ADU contractor in Harbor City? DECOMA designs, permits through LADBS, and builds garage-conversion, junior, and detached ADUs — from our own shop in 90710.

Why harbor city adu

Harbor City ADU contractor — from a shop in your zip code

If you're searching for an ADU builder in Harbor City, here's our home-field claim: DECOMA's shop and corporate office has been at 25941 Frampton Avenue, 90710 since 1978. We design, permit, and build accessory dwelling units across Harbor City, Harbor Gateway, Harbor Pines, and the Lomita border with one licensed team — and the trucks roll out of the neighborhood, not across the county.

How much does an ADU cost in Harbor City?

The honest answer: it depends on what you build. A garage-conversion ADU, a detached new-build ADU, and a junior ADU are different projects with different price tags — then site work, sewer, and finish level move the number further. We don't quote a figure before we've walked the lot. On the free consult you get an honest range, and we design backward from your real budget — for a unit that adds rental income and resale value on a lot you already own.

Types of ADUs we build

  • Detached ADU — Harbor City's postwar lots typically run around 6,000 sq ft, which is real room for a standalone unit; state law generally allows up to 800 sq ft regardless of lot coverage limits.
  • Garage conversion — reusing the existing garage; usually the fastest path and frequently parking-exempt.
  • Attached ADU — added onto the existing house where that suits the lot better.
  • Junior ADU (JADU) — up to 500 sq ft within the existing home, sometimes called a granny flat or in-law unit.

ADU rules and zoning in Harbor City

The thing owners get wrong first: Harbor City is part of the City of Los Angeles. Your ADU permits run through LADBS — not a standalone city Building & Safety counter like Torrance at 3031 Torrance Blvd or Redondo Beach at 415 Diamond St. Different submittal process, different corrections cycle, different inspector scheduling. The second thing: Harbor City's mix of postwar single-family, light-industrial, and small-lot commercial means zoning varies sharply block to block, and community-plan or specific-plan overlays are the usual source of an unexpected review step. Both are exactly what the feasibility walk exists to catch — before you pay for design.

The LADBS permit process

ADUs review on the state's ministerial pathway against objective standards, which keeps the process predictable — but LADBS is a big department, and knowing how to carry a set through it is half the job. The counter that serves the Harbor area is the San Pedro Development Services Center at 638 S. Beacon St, open Tuesday and Thursday — we file there, run the corrections cycle directly, and schedule inspections without a third-party expediter. LADBS doesn't publish a standard plan-check turnaround, so we get the current answer from the department and give you a schedule built on it, not on optimism.

Ground conditions worth knowing

Most of Harbor City sits on alluvial flats where standard ADU foundations do fine, rising toward the Palos Verdes shelf on the western edge. The exception: Ken Malloy Harbor Regional Park sits on a historic wetland, and parcels near it can carry a high water table — a foundation and drainage question we settle on the lot walk, not in excavation.

Why DECOMA for your Harbor City ADU

Proximity here isn't a marketing line — it's a scheduling fact. The shop is minutes from most Harbor City lots, so site visits, punch lists, and the small mid-project decisions that stall other jobs simply don't wait. The people who draw your ADU are the people who build it: one contract, one schedule, one CSLB Class A/B license (#375508). Nearby, the Cabrillo Bungalows in San Pedro and our South Shores Home show the residential end of the portfolio, and the same team serves the rest of Harbor City, Torrance, and San Pedro.

Start with a free consultation — or call the shop; we're already in the neighborhood.

How we run it

Scope to sign-off.

  1. 01

    Free ADU feasibility & lot walk

    Harbor City's postwar lots typically run around 6,000 square feet — real room for a detached ADU — but zoning varies sharply block to block, and community-plan overlays are the usual source of a surprise review step. We check zoning, setbacks, sewer, and service capacity on site, and because the shop is minutes away, the lot walk happens this week, not next month.

  2. 02

    Design, plans & LADBS permits

    Harbor City is part of the City of Los Angeles, so plans go through LADBS — not a standalone city counter like Torrance or Redondo. We draw to LADBS conventions and carry the set through plan check and corrections directly, working through the San Pedro Development Services Center that serves the Harbor area.

  3. 03

    Build & certificate of occupancy

    Foundation, frame, MEP, finishes, and any sewer, panel, or service upgrade — structural work self-performed under our Class A/B license, with crews that start their morning in 90710. Typically 5–9 months on site, ending in final inspection and certificate of occupancy.

Why DECOMA

One license, three disciplines, forty years.

Family-run South Bay general contractor since 1978. We design, build, and manage — under one license — so the team you start with is the team that hands you keys and the team that answers the phone when something needs fixing in year ten.

Years building
48+
Projects delivered
3,000+
Repeat clients
300+
CSLB Class
A/B

FAQ

Common questions.

Which building department handles a Harbor City ADU?
Harbor City is part of the City of Los Angeles, so ADU permits run through LADBS rather than a standalone city department — a different process from neighboring Torrance or Lomita, which run their own counters. The nearest LADBS counter is the San Pedro Development Services Center at 638 S. Beacon St, open Tuesday and Thursday. We file, correct, and carry inspections through LADBS directly.
How much does an ADU cost in Harbor City?
It depends on type and size — a garage conversion, a detached new-build ADU, and a junior ADU are very different projects, plus site work, sewer, and finishes. We don't quote a number before we've seen the lot. On the free consult you get an honest range, and we design backward from your real budget.
How long does a Harbor City ADU take?
LADBS doesn't publish a standard plan-check turnaround, so we won't invent one — we get the current answer from the department and build an honest schedule around it. Construction typically runs 5–9 months for most ADUs. What we control is the corrections cycle: we draw to LADBS conventions up front, which is where first-time filers lose their months.
Can I build a detached ADU on my Harbor City lot?
Often yes. Typical Harbor City lots run around 6,000 square feet — postwar single-family parcels with real backyards — and state ADU law generally allows a detached ADU up to 800 square feet regardless of lot coverage limits. The catch is that zoning varies sharply block to block here, so the feasibility check matters more than in a uniform R-1 tract.
Is there anything unusual about building near Ken Malloy Harbor Regional Park?
Parcels near the park can carry a high water table — it sits on a historic wetland. That shapes foundation and drainage decisions for an ADU, and it's exactly the kind of thing we check on the lot walk rather than discover in excavation. Most of Harbor City sits on alluvial flats where standard foundations do fine.
Do you do garage-conversion ADUs and junior ADUs (JADUs)?
Yes — detached ADUs, attached ADUs, garage conversions, and junior ADUs up to 500 square feet within the existing home. We pick the type on the lot walk based on your goal, your lot, and cost and schedule.
Why hire a Harbor City-based contractor for an ADU?
Our shop and corporate office has been at 25941 Frampton Ave since 1978 — most Harbor City lots are minutes away. Site visits, inspections, and the small mid-project decisions that stall a job waiting for someone to look at it all happen faster when the contractor starts the morning in your zip code.

Service areas

Harbor city adu across the South Bay.

Born in Harbor City, working across LA County since 1978. Same crew, same license number, same shop at 25941 Frampton Ave, Harbor City.

Talk to a contractor

Tell us about your project.

One business day for a scope, timeline, and budget range. CSLB #375508 A/B.

Request consultation(310) 418-0258