Fast, Reliable Home Addition Contractor Across San Marino
A Home Addition Contractor in San Marino, CA typically charges $180,000 – $450,000 for a full room addition and $130,000 – $275,000 for a detached ADU or garage conversion, with permits and architectural review adding 8 – 14 weeks before construction starts. That’s the straight answer most firms won’t give you over the phone. We’re Home Addition Contractor in San Marino specialists, and we put every number in writing before you sign anything.
San Marino is not like Alhambra or Temple City. The Architectural Review Board here will reject a design that doesn’t match your primary residence’s historic revival style, and that single fact reshapes every budget and timeline on this page. We know what gets approved, what gets flagged, and how to schedule around it so your project doesn’t sit half-finished waiting on a committee. Call (254) 602-5618 for a free estimate and we’ll walk your lot with you.
Key Takeaways
- Room additions in San Marino run $180,000 – $450,000 depending on square footage and seismic scope; sunrooms run $95,000 – $180,000.
- Architectural Review Board approval takes 6 – 10 weeks in San Marino, and design compliance must be resolved before submittal.
- Original carriage houses and detached garages on estate lots are the most common conversion targets, but most need full electrical and plumbing replacement.
- Every project comes with a written price, a written 365-Day Done Right Promise, and crews that show up in a real arrival window.
Why Lodgewick ADU Builders Is San Marino’s Preferred Home Addition Contractor Company
Lodgewick ADU Builders is the ADU Builders in San Marino for the Kingswell family, established in 2010. Russ Delmar leads the San Marino work, and he’s the person who walks your property, reviews your structures, and signs the proposal. That person-level accountability matters in a city where the building department expects documentation, not handshakes. Homeowners on Lorain Road, St. Albans Road, and around Lacy Park have seen our crews enough to know we park respectfully, keep the site clean, and don’t leave a half-built addition exposed to the neighborhood.
Our reviews from San Marino customers consistently mention three things: the written price didn’t change, the crew arrived in the window we gave, and when something needed adjusting, a live person answered the phone. That last point is a written policy, not a slogan. A live person answers our line 24/7. No voicemail loops.
We coordinate response times to San Marino from our Los Angeles scheduling office, and most estimates happen within a few business days of your call. Once work begins, we plan around the Architectural Review Board calendar, not against it. That’s the local knowledge that keeps a San Marino project moving while other contractors stall at plan check.
Sunroom Addition in San Marino
A Sunroom Addition in San Marino costs between $95,000 and $180,000 depending on whether it’s a conditioned space with HVAC or a three-season room, and the architectural review adds roughly six to ten weeks before you’re permitted. On San Marino’s large estate lots, sunrooms typically go onto the rear elevation facing the garden, and the Board will require the new roof pitch and window proportions to match the original house’s revival style, whether that’s Spanish Colonial Revival or a formal Tudor.
This is not a bolt-on. It’s a structural room with foundation, glazing, and a roof that has to look like it was always there. That’s the design bar in San Marino, and we meet it on every project before submittal.
Design Compliance Before Submittal
We resolve material choices, window mullion patterns, roofline pitch, and stucco or siding color before the architectural packet goes in. A contemporary glass box won’t get approved here. A carefully proportioned sunroom with divided-light windows and a tile roof detail will.
What the Permit Packet Includes
Your submittal packet needs architectural drawings, a materials board, site plan, structural calculations, Title 24 energy compliance, and a hazmat report if the tie-in touches pre-1950 construction. We file all of it under our name. You don’t chase the city.
Room Addition Contractor in San Marino
A Room Addition Contractor in San Marino works on homes built between roughly 1920 and 1955, which means the addition has to match formal revival architecture while being seismically tied to a structure that predates modern code. You’re looking at $180,000 – $450,000 for a true room addition here, and the number moves based on whether the addition ties into existing knob-and-tube or galvanized plumbing, whether the foundation is post-and-pier, and what the Architectural Review Board requires visually.
Most room additions in San Marino are primary-suite additions off the rear of the house or expanded kitchens that push into a side yard. On estate lots off Huntington Drive and Oak Knoll Avenue, the properties are big enough that a first-floor addition doesn’t compromise the garden, but the Board still weighs how the new volume reads from the street.
Seismic and Systems Work Is Assumed
A 1928 house doesn’t have a modern shear wall at the point where you’re opening the envelope. We calculate for that, permit for it, and build it. Expect foundation upgrades, lateral bracing, and a full electrical subpanel rather than a tap off an existing 60-amp service.
Kitchen and Primary Suite Additions
Kitchen additions and primary suites represent the bulk of room addition work in San Marino. Both require moving plumbing, upgrading ventilation, and matching interior trim profiles to the original house. That trim work is what the Board notices least but what homeowners appreciate most five years in.
Trusted Brands We Service in San Marino
We work directly with prefab and panelized systems from Cover, Dvele, and Boxabl, and we match each to your lot, your architectural style, and your timeline. For San Marino specifically, the decision often comes down to whether the system’s cladding, fenestration, and roofline can be adapted to pass Architectural Review Board scrutiny. We’ve sequenced Dvele panelized units on estate lots where a traditional detached ADU worked better than a garage conversion, and we keep material lead times local so San Marino customers aren’t waiting on a factory schedule that doesn’t account for their review calendar. When a system can’t meet San Marino’s design bar, we say so before you spend a dollar.
Common Home Addition Contractor Problems We See in San Marino Homes
- Contemporary designs that get rejected at review. A stock ADU plan with flat roofs or modern cladding will bounce at the Architectural Review Board, restarting your submittal clock. We design to the primary residence’s revival style before the packet goes in.
- Asbestos discoveries at plan check. Pre-1950 floor tile mastics, popcorn ceilings, and pipe insulation are common in San Marino’s original carriage houses. The building department flags this during plan check, and remediation costs surprise homeowners who skipped a pre-permit hazmat assessment.
- Overheating garage conversions. San Marino sits in the San Gabriel Valley floor where summer highs push into the mid-to-high 90s°F with little coastal breeze. Converting an uninsulated original garage without a properly sized ductless mini-split leaves the space unlivable by July.
- Knob-and-tube wiring and galvanized supply lines. Most pre-1950 outbuildings in San Marino were wired and plumbed with materials that don’t come close to meeting current California Title 24 standards. A conversion isn’t cosmetic; it’s a full systems replacement.
On a 1920s Spanish Colonial Revival estate off Lorain Road, our crew converted an original detached carriage house into an ADU, matching the main house’s clay barrel-tile roofline and stucco detailing, then replaced the galvanized supply lines and knob-and-tube wiring before adding a ductless mini-split to fight the San Gabriel Valley’s windless 95-degree summers. We also ran a pre-permit hazmat assessment that caught asbestos in the floor tile mastic, letting the homeowner absorb remediation into the budget instead of stalling mid-build. That’s the sequence that saves San Marino homeowners money and calendar time.
Pricing for Home Addition Contractor in San Marino, CA
You should never have to call just to get a ballpark. Here are the ranges we quote in San Marino:
- Sunroom addition: $95,000 – $180,000
- Room addition (single room, conditioned): $180,000 – $280,000
- Primary suite addition: $250,000 – $450,000
- Detached ADU or carriage house conversion: $130,000 – $275,000
- Bump-out addition: $70,000 – $140,000
What moves the number in San Marino is design review scope, seismic retrofit scope, hazmat remediation, and the level of finish matching the main house. A written price comes before any work starts. Always. If the scope changes, the written change order comes before the additional work does. Call (254) 602-5618 to schedule your free estimate; we’ll walk the property and give you a real number in writing.
We Also Serve Cities Near San Marino
Our crews work throughout the western San Gabriel Valley. In addition to covering every neighborhood in San Marino, we serve homeowners in San Gabriel, Alhambra, Pasadena, and South Pasadena. San Marino’s design-review requirements are the strictest in the group, which means if we can build here, we can build anywhere in the surrounding area.
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 Home Addition Contractor in San Marino
San Marino’s Architectural Review Board requires every ADU to match the primary residence’s historic revival style in materials, roofline, and detailing, and that review adds roughly six to ten weeks to the permit timeline. Alhambra and Temple City don’t impose the same design-compliance gate. Call (254) 602-5618 and we’ll show you a realistic calendar for your specific property.
Yes, and it’s the most common ADU path in San Marino, but almost every pre-1950 carriage house needs seismic retrofitting, full electrical replacement, and replumbing before it meets current code. We handle all of it, and we file the architectural packet under our name. Get a free assessment by calling (254) 602-5618.
It will if the conversion skips insulation and a properly sized ductless mini-split. San Marino’s inland San Gabriel Valley location means windless days in the mid-to-high 90s°F, and an uninsulated original garage becomes unlivable. We spec insulation and HVAC as non-negotiable items in every conversion quote.
Yes, and we recommend it before you lock in a budget. The San Marino building department will flag asbestos in floor tile mastics, popcorn ceilings, and pipe insulation during plan check, and remediation costs are much easier to absorb when they’re in the original proposal. We run the assessment pre-permit on every conversion.
We front-load design compliance so the submittal packet is complete and approvable on the first pass, then we sequence the build around the review calendar. Demolition and structural work start after approval, and material orders are timed so nothing sits exposed. You get a written schedule before we start.
Schedule Your Free Estimate in San Marino
If you’re planning a room addition, sunroom, garage conversion, or detached ADU in San Marino, start with a real conversation. Russ Delmar walks the property, reviews your existing structures, and gives you a written price and a written 365-Day Done Right Promise before any work begins. A live person answers our line 24/7. Call (254) 602-5618 today.
Written by Russ Delmar, Owner at Lodgewick ADU Builders, serving San Marino and the western San Gabriel Valley.