A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateFast, Reliable Home Addition Contractor Across Corte Madera
Adding a bedroom, sunroom, or bump-out to a Corte Madera home usually means opening up walls built in the 1950s, 1960s, or 1970s. What you find inside those walls changes the real cost faster than anything else. We are Home Addition Contractor specialists who write that reality into your contract from day one: inspection first, allowances written down, and any surprise priced and approved in writing before we touch it. If you’re planning an addition in Corte Madera, call us at (707) 760-0502 for a free estimate and we’ll walk your lot, check your existing structure, and give you a written number that accounts for what’s actually behind your drywall.
Why Lodgewick ADU San Francisco Is Corte Madera’s Preferred Home Addition Contractor Company
Corte Madera homeowners call us because our quotes survive contact with their walls. We’ve worked on enough post-war ranches along Tamalpais Drive, near Chapman Creek, and up in the flats to know what’s likely waiting behind an original 1960s panel: aluminum branch wiring, ungrounded circuits, and framing that has been breathing Bay moisture for sixty years. Russ Delmar leads our team here, and he has walked dozens of Corte Madera yards to plan additions that keep mature oaks and creek buffers intact.
Our crews show up in a defined arrival window, wear uniforms, and carry background checks. The price we write down before work starts is the price you approve before work starts; if something changes, you get a written change order and you sign it before we proceed. That’s The Kingswell Guarantee, and it applies to every addition, garage conversion, and Corte Madera project we take on. When a homeowner asks what sets us apart, we point to the 365-Day Done Right Promise: if the work isn’t right, we come back and make it right, in writing, for a full year.
Bedroom Addition Contractor in Corte Madera
A bedroom addition in Corte Madera typically runs $180,000 to $340,000 for a ground-floor addition on a ranch-style lot, with the final number driven by what the permit inspection finds when we open the wall between old and new. Our Home Addition Contractor team has done enough of these to know the pattern: the moment drywall comes down on a 1960s original, the electrical reality changes. We plan for that before the saw comes out.
Electrical Reality on Post-War Ranches
In Corte Madera, home additions on the many 1950s-1970s ranch-style homes often require bringing outdated knob-and-tube or aluminum wiring up to current code the moment walls are opened. That can mean a panel upgrade, AFCI and GFCI breaker requirements, and re-feeding circuits to the new bedroom. Neighboring cities with newer housing stock rarely trigger this. We build allowances into the written quote from the start, so a panel upgrade is a priced line item, not an emergency surprise.
Ground-Floor Bedroom on a Creek-Side Lot
On a lot near Chapman Creek, a ground-floor bedroom addition has to respect riparian setbacks. We handle that paperwork and the buffer measurements before framing begins. Corte Madera’s flat, creek-side lots and older post-war housing stock create ADU and addition opportunities, but the flood zone and hillside regulations shape designs more than in neighboring cities. We factor those constraints into the first drawing, not the change order.
Sunroom Addition in Corte Madera
A sunroom addition in Corte Madera generally costs $90,000 to $180,000 depending on square footage, glazing, and whether the new room ties into the existing foundation or sits on a separate slab. The Bay’s moisture exposure matters here more than the sun: any sunroom we build gets proper waterproofing and ventilation to prevent mold in the damp microclimate. That’s a local requirement we don’t skip, even when it isn’t the cheapest route.
Foundation and Moisture Control
Proximity to San Francisco Bay moderates Corte Madera’s temperatures, but it also pushes damp air into every wall cavity. A sunroom built on a wet slab will fail, so we spec capillary breaks and flashing details that shed water instead of trapping it. We’ve taken apart enough failed sunrooms in Corte Madera to know what a rotted sill plate looks like before it’s covered over.
Opening a Wall for More Light
Many Corte Madera sunroom additions start as a bump-out from an existing living room or family room. When we cut that opening, we find what the original builder left: sometimes ungrounded wiring, sometimes water-rotted framing near the base plate. We stop, document, and hand you a written change order with a number attached. You approve it, then we proceed. No one touches a new wire or a new stud without your signature.
Trusted Brands We Service in Corte Madera
We work with established ADU and addition materials that hold up in Corte Madera’s damp Bay climate. That includes James Hardie siding for exterior additions on ranch homes, Tuff Shed for prefab accessory structures where a site-built approach isn’t necessary, and Plant Prefab when a homeowner wants a factory-built module delivered and set on a Corte Madera lot. We stock common parts and materials locally for Corte Madera customers, which shortens lead times when a change order adds a window, a door, or a weather barrier mid-project. When a lumber yard on Tamalpais Drive has what we need, your schedule doesn’t slip.
Common Home Addition Contractor Problems We See in Corte Madera Homes
- Electrical surprises after drywall comes down. Corte Madera contractors discover knob-and-tube or ungrounded wiring only after a wall is opened, then hit the homeowner with an unapproved emergency change order. We instead document the condition, price the fix, and get written approval before proceeding.
- Water-rotted sill plates near the creek. A crew opens a wall on a post-war ranch and finds rotted framing from the damp Bay microclimate. If they patch over it instead of installing proper flashing and capillary breaks, mold follows. We replace and protect, and the repair goes in the written record.
- Stop-work orders from riparian setbacks. An addition near Chapman Creek triggers a stop-work order because the builder didn’t account for the creek buffer, leaving a framed opening exposed to Corte Madera rain for weeks. We measure setbacks before the first board goes up.
- Undersized service panels on 1950s homes. Many original Corte Madera ranches have 100-amp panels that can’t carry a new bedroom or sunroom. We include a panel upgrade in the written estimate when the existing service is undersized.
Pricing for Home Addition Contractor in Corte Madera, CA
Here are honest ranges for Corte Madera’s market. A bedroom addition typically runs $180,000 to $340,000. A sunroom addition runs $90,000 to $180,000. A bump-out runs $60,000 to $120,000. A second-story addition on a Corte Madera ranch runs $280,000 to $450,000. A garage conversion runs $120,000 to $200,000. The biggest cost driver on post-war homes is the electrical and framing upgrade triggered by the permit, and we write allowances for that into the contract so the final number doesn’t move without your approval. Call (707) 760-0502 for a free, written estimate specific to your house and your lot.
We Also Serve Cities Near Corte Madera
Our crews serve Corte Madera, San Rafael, Sausalito, Richmond, and San Francisco. Each project gets the same written price, defined arrival window, and 365-Day Done Right Promise. If you’re in a neighboring city and planning an addition, you’ll get the same straight numbers and the same guarantee.
Serving Corte Madera, CA - Our Local Coverage Area
We’re based in the Corte Madera 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 Corte Madera
Expect aluminum branch wiring or ungrounded circuits, and possibly a failed 100-amp panel, on many 1960s Corte Madera ranches. The permit inspection will generally require AFCI and GFCI protection, which means panel work. We price this as a written allowance before we start, so the surprise is handled and approved, not sprung on you after demolition. Call (707) 760-0502 to talk through your home’s likely condition.
Yes. Corte Madera enforces riparian setbacks along Chapman Creek, and any addition within the buffer needs review before a permit is issued. We measure the setback and file the paperwork early, because an unapproved addition near the creek will get a stop-work order. An exact site review is free; call (707) 760-0502.
We stop work, document the rot with photos and measurements, and issue a written change order with a firm price to replace the damaged framing and install proper flashing and capillary breaks. You approve that number before we proceed. Patching over rot in Corte Madera’s damp air creates mold; we don’t do it.
Possibly, depending on how much of the existing structure is altered. Marin County and Corte Madera follow California energy code, and substantial additions can trigger wall insulation, attic insulation, or glazing requirements on the existing portion. We tell you exactly what the permit reviewer flags and include those line items in the written estimate before work begins.
If the existing foundation or sill plates show moisture intrusion, yes. Corte Madera’s proximity to the Bay means even older homes that haven’t flooded still carry damp soil conditions. We specify capillary breaks, drainage details, and vapor barriers where needed. That work is priced and written into your contract, not added later by surprise.
Planning an addition on a post-war Corte Madera ranch? Call (707) 760-0502 to schedule a free estimate. We’ll walk the lot, look at what’s behind your walls, and put a real number in writing before any work starts.
Written by Russ Delmar, Owner at Lodgewick ADU San Francisco, serving Corte Madera since the Kingswell family established the company in 2010.
