ADU Company in San Marino, CA
San Marino is one of the few cities in Los Angeles County where adding an ADU means matching a 1920s Spanish Colonial Revival estate rather than simply shipping in a prefab box. Our work here focuses on large historic lots, original carriage houses and garages from the 1920s through 1950s, and summer heat that regularly pushes into the mid-to-high 90s°F with no coastal breeze. Lodgewick ADU Builders handles accessory dwelling units, garage conversions, and home additions in San Marino under The Kingswell Guarantee: a written price before work starts, a defined arrival window, a clean job site, and a written 365-Day Done Right Promise on every project. Call (254) 602-5618 for a free estimate.
Why San Marino Homes Are Different
San Marino’s housing stock is dominated by large single-family estates built between roughly 1920 and 1955 in formal revival styles – Spanish Colonial Revival, Tudor Revival, and Monterey Colonial among them. Many of these lots exceed 15,000 to 25,000 square feet and include original detached carriage houses, garages, and secondary service structures that are, on paper, ideal ADU conversions. The reality is more complicated. Those outbuildings were often wired with early Romex or knob-and-tube and plumbed with galvanized supply lines, which means almost every conversion requires full electrical replacement, replumbing, and seismic retrofitting before it meets current California Title 24 standards.
Then there’s the design review. San Marino’s Architectural Review Board requires any ADU to match the primary residence’s historic architectural style in materials, roofline, and detailing. That constraint does not exist in the same form in neighboring Alhambra or Temple City. A homeowner who buys a prefab ADU without an architect-led, historically sympathetic design phase is likely to hit a wall at plan check. We’ve seen this pattern enough that our San Marino process always includes a design review of the primary home before a permit is submitted. It saves months and thousands of dollars downstream.
Heat is the other defining condition. San Marino sits on the inland San Gabriel Valley floor, and garage-conversion ADUs with minimal original insulation overheat severely by June. Proper wall and ceiling insulation and a correctly sized ductless mini-split are not upgrades here – they are the difference between a livable unit and a room nobody uses between May and October.
Our Main San Marino Services
The two things San Marino homeowners call about most are garage conversions and full ADU builds, with home additions close behind.
Home Addition Contractor in San Marino
Home additions in San Marino almost always involve matching a historic facade. Adding square footage to a 1930s Tudor means matching brick, stucco texture, window proportions, and roofline details, and the Architectural Review Board reviews all of it. We start every addition with a survey of the existing structure and a design that respects the original architecture rather than fighting it. The result is a home that looks like it was always that size. For the full scope of what a San Marino addition involves, see our Home Addition Contractor in San Marino page.
Garage Conversion Contractor in San Marino
San Marino’s original detached garages and carriage houses are the most common ADU conversion targets in the city, but they hide costs. Many pre-1950 structures contain asbestos in floor tile mastics, popcorn or textured stucco ceilings, and pipe insulation, and the building department flags this during plan check. We recommend a pre-permit hazmat assessment before anyone locks in a budget, because remediation costs frequently surprise homeowners who assumed a simple conversion. For what a garage conversion costs and how we handle the hazmat piece, see our Garage Conversion Contractor in San Marino page.
ADU Builders in San Marino
Building a new detached ADU on a San Marino estate lot means working within setback rules, historic design review, and the reality that a 20,000-square-foot lot still needs a structure that looks like it belongs next to a 1928 Spanish Colonial. We work with prefab manufacturers like Abodu and Cover where they fit the lot and the architectural language, and we bring in custom framing where they don’t. Every ADU we build in San Marino goes through a design review against the primary residence before permit submission. For specific ADU costs, timelines, and what the Architectural Review Board actually requires, see our ADU Builders in San Marino 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 Marino
We work hands-on with Abodu, Cover, and James Hardie materials in San Marino, and we’ll match the right system to the lot, the historic style, and the budget. Hardie siding shows up often in San Marino because it can be detailed to read as traditional board-and-batten or shingle while holding up to valley heat. For the full range of what we service, see our brands.
Pricing for ADU Company in San Marino, CA
| Service | Typical range in San Marino |
|---|---|
| Garage conversion to ADU | $120,000 – $165,000 |
| Detached new-build ADU | $265,000 – $390,000 |
| Prefab ADU (turnkey, including site work) | $225,000 – $370,000 |
| Home addition (primary residence, moderate build) | $145,000 – $265,000 |
| Seismic retrofit on existing garage/carriage house | $14,000 – $38,000 |
| Full electrical replacement in converted outbuilding | $9,000 – $22,000 |
| Replumbing with new supply lines | $7,000 – $18,000 |
| Asbestos remediation (floor tile, ceilings, pipe wrap) | $4,500 – $16,000 |
| Ductless mini-split system (installed, sized) | $6,000 – $13,000 |
| Insulation upgrade (walls and ceiling for ADU) | $5,000 – $12,000 |
| Architectural Review Board design package | $6,000 – $18,000 |
What pushes a San Marino project toward the top of these ranges is the historic-design work: matching a primary residence’s original materials and detailing costs more than a clean-slate build. Then there are the retrofit costs most estimates don’t include – knob-and-tube replacement, galvanized repipe, seismic work, and hazmat remediation. Every Lodgewick estimate is a written price before work starts, and that price does not change at the door.
Neighborhoods We Serve in San Marino
We work throughout San Marino, from the estates along Huntington Drive and Lombardy Road to the streets around Lacy Park and the neighborhoods near the Huntington Library’s western edge. Each area has its own rhythm, but the underlying housing stock is consistent: large revival-style homes from the 1920s through 1950s with detached garages and carriage houses that lend themselves to ADU work.
- Lacy Park area
- Lombardy Road estates
- Huntington Drive corridor
- Near the Huntington Library
- Virginia Road and surrounding streets
For most San Marino estimates we can be on site within a few business days of the first call, and the written quote follows the site visit.
Service Area – Cities Near San Marino
San Marino sits at the center of our West San Gabriel Valley coverage, and homeowners on the city’s edges often ask whether we work next door. We do. We serve San Gabriel, CA directly east, Alhambra, CA to the south, Pasadena, CA to the north, and South Pasadena, CA to the west. Each city has its own permitting quirks, but The Kingswell Guarantee travels with every job.
Serving San Marino, CA - Our Local Coverage Area
We’re based in the San Marino 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 Marino
For most San Marino addresses we can schedule a site visit within a few business days of your first call. We’re a local operation serving San Marino directly, not dispatching from across the county. Call (254) 602-5618 and we’ll get a time on the calendar.
Yes. San Marino requires any ADU to match the primary residence’s historic architectural style in materials, roofline, and detailing. This is stricter than what neighboring cities require, and it means the design phase matters more in San Marino than almost anywhere else in the region. We handle this by bringing the design package before the permit is submitted, not after the board rejects it.
Yes. Every Lodgewick project gets a written price before any work begins, and that price does not change at the door. If we find something during demolition that wasn’t in the scope, we talk to you about it in writing before touching it. No change orders without your sign-off. Call (254) 602-5618 for a free estimate.
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 Marino Customers Say
"Built a backyard unit for my mother in law. They handled the permits, gave me a real timeline, and stuck to it within a few days. The written price is what we paid, which anyone who's done construction knows is rare."
- Dennis Fairchild"Garage conversion into a studio for our teenager. Honest about what was realistic and what wasn't, finished close to schedule, and cleaned up the site daily."
- Marcus Beaumont"I was nervous about adding on but they walked me through every step and every cost before we started. No surprise change orders halfway through like I'd heard horror stories about."
- Eleanor Pratt