A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateFast, Reliable ADU Builders Across Strawberry
Adding an accessory dwelling unit in Strawberry means adding a small house, a lodge, to your larger property. It’s the smartest way to gain living space on a lot you already own. But building one here is not the same as building one in Mill Valley or San Rafael. Strawberry is unincorporated Marin County, which changes the permitting path, the septic review, the erosion rules, and the timeline. We know exactly what that means for your hillside lot, because we do this work in Strawberry every week. Need a straight answer about cost, timeline, or where to even start? Call (707) 760-0502 for a free estimate.
Why Lodgewick ADU San Francisco Is Strawberry’s Preferred ADU Builders Company
Our ADU Builders team works in Strawberry regularly, and the first thing we tell homeowners is the truth about county permitting. Strawberry residents do not file ADU permits with Mill Valley. They file with Marin County. That one fact catches a lot of people off guard, and plenty of contractors bid the job as if it did not matter. Then the schedule slips by months and the change orders start. We price Strawberry jobs for the review process Strawberry actually requires.
Every Strawberry project runs under The Kingswell Guarantee. That means a written price before any work starts, a defined arrival window, a clean job site, and a written guarantee on the completed ADU. If something is not right within 365 days, we come back and fix it. Free. That promise is in writing on every single build, and on every garage conversion and home addition we do here. Russ Delmar leads our Strawberry work, and he makes sure every commitment is honored.
We answer the phone. A live person picks up 24 hours a day, seven days a week. No voicemail loops when you have a question about your permit status, your foundation inspection, or your framing allowance. That matters when a Marin County reviewer flags something on a Thursday afternoon and you need answers before the weekend.
ADU Contractor in Strawberry
An ADU Contractor in Strawberry does a lot more than frame walls. On a 1950s or 1960s wood-framed hillside home, the job often starts with what is behind the drywall and under the siding. Outdated wiring. Rotted sill plates. Drainage that has been quietly moving water toward the foundation for fifty years. Opening those walls for an ADU tie-in means dealing with what a Marin County inspector will find, and the county will look. We handle it by inspecting first, writing allowances into the contract, and never surprising you at the door. A typical detached ADU in Strawberry runs $280,000 to $420,000 depending on hillside access, foundation work, and seismic upgrades. A garage conversion runs $160,000 to $250,000.
Detached and Junior ADU Work
Detached ADUs on narrow Strawberry lots often require a crane or tracked equipment to reach the build site, especially above Seminary Drive or along the ridge streets where driveways climb at grade. We plan for that access cost upfront, not after excavation starts. Junior ADUs, or JADUs, are smaller conversions inside the footprint of the existing home, and they move faster through Marin County review because they trigger fewer septic and fire-safety requirements.
Prefab and Modular Installations
For lots where a traditional stick build would drag through winter rains, we install prefab and modular units from Abodu, Cover, and Dvele. These units arrive on a truck and get set on a prepared foundation, which shortens the site work window considerably on a sloped Strawberry lot. The county still reviews the foundation, drainage, and fire-resistant materials, but the structure itself arrives engineered and ready.
ADU Design in Strawberry
ADU Design in Strawberry starts with the lot, not the floor plan. A 600-square-foot design that works on a flat suburban lot in the East Bay will not work on a hillside off Seminary Drive with a 15-degree slope and a Marin County erosion-control overlay. We design around drainage first. The ADU has to shed water away from the existing home and the new foundation, or you will fail the county’s erosion inspection the first winter. Typical design and engineering fees for a Strawberry ADU run $18,000 to $35,000, depending on whether the lot requires a soils report, a geotechnical review, or fire-hardening details.
Studio ADU and Garage Conversion Plans
A studio ADU in the 400-to-500-square-foot range is the most practical option for Strawberry lots with limited flat area. We design these as single-level units with low-profile roofs so they do not trigger the county’s more aggressive visual-impact or tree-protection review. Garage conversions need structural assessments, because many 1960s Strawberry garages were built on minimal footings never meant to carry living space.
Wildfire and Drainage Design
Strawberry sits in a Marin County high-fire-severity zone, so the design has to use ignition-resistant siding, ember-resistant vents, and defensible space that is documented in the permit drawings. We use James Hardie siding and Tuff Shed engineered structures where they fit the lot and the budget. Every design we submit includes a drainage plan that accounts for winter rain flowing downhill toward Richardson Bay.
Trusted Brands We Service in Strawberry
We work with Abodu, Cover, and Tuff Shed on Strawberry projects because these manufacturers build units that hold up to coastal moisture and meet California energy and fire codes without a fight. We do not sell you a brand. We match the brand to the lot. A narrow hillside parcel with constrained crane access might be better served by a panelized Cover unit than a wide-load Tuff Shed. If a Strawberry homeowner wants the durability of James Hardie siding on a custom build, we spec it early in the design so the Marin County fire review goes smoothly. Parts and service calls for these systems are available to Strawberry customers without the long turnaround that comes from dealing with a manufacturer directly.
Common ADU Builders Problems We See in Strawberry Homes
- Aluminum branch wiring inside 1960s walls. When we open a wall to tie in an ADU subpanel, we often find aluminum wiring that Marin County code will not permit to remain exposed. This is not a surprise we spring on you mid-build; we write a line-item allowance for circuit replacement before framing starts.
- Rotted sill plates and foundation damage from hillside drainage. Decades of water moving downslope toward a structure will rot the bottom plate of the framing. On a recent Strawberry job, we had to sister several floor joists and replace the sill plate before the county inspector would sign off on the ADU wall tie-in.
- Septic and sewer conflicts on older lots. Many Strawberry homes are on septic systems or aging sewer laterals, and a new ADU adds bedroom count that the county uses to recalculate septic capacity. If the system will not support the added load, the ADU gets smaller or the septic system gets upgraded. We flag this in the first site visit, not after plans are drawn.
- Access and excavation on steep lots. On hillside streets like those off Seminary Drive, getting a mini-excavator to the ADU footprint can require temporary road protection, tree limbing, or even hand-digging in tight spots. Contractors who bid Strawberry jobs without walking the site will underprice the access work and then ask for more money later. We walk every lot before we bid.
Pricing for ADU Builders in Strawberry, CA
A detached ADU in Strawberry typically runs $280,000 to $420,000, and a garage conversion runs $160,000 to $250,000. A junior ADU inside the existing home footprint is the most affordable path at $110,000 to $180,000. Design and engineering fees add $18,000 to $35,000 depending on geotechnical and fire-safety requirements. The biggest cost drivers on Strawberry jobs are hillside foundation work, drainage and erosion control, seismic retrofitting on older homes, and the Marin County permitting timeline itself, which adds soft costs even before construction begins. We give you a written line-item bid that shows exactly what each part costs, and we never change the price at the door. Call (707) 760-0502 to schedule a free estimate on your Strawberry ADU.
We Also Serve Cities Near Strawberry
Our work in Strawberry often extends to nearby communities. We serve Hayward in the East Bay for flat-lot ADU and garage conversion work, Martinez for detached units on larger parcels, and Moraga and Orinda for hillside lots that face similar drainage and fire-review challenges to what we see in Strawberry. The permitting path differs in each city, so we handle the local filings for you.
Serving Strawberry, CA - Our Local Coverage Area
We’re based in the Strawberry 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 Builders in Strawberry
Plan on six to ten months for Marin County to review and issue an ADU permit for a Strawberry hillside lot. This is longer than what homeowners in incorporated Mill Valley experience, because the county runs a separate planning department, and hillside parcels with slopes over 15 percent trigger erosion-control and geotechnical review. Some projects need a Marin County planning commission hearing. We prepare your submittal to clear the first review cycle, which saves months compared to resubmitting. Call (707) 760-0502 and we will walk you through your lot’s specific timeline.
You pay for it through a written allowance, not a surprise change order. On a 1960s Strawberry home near Seminary Drive, our crew opened a wall to tie in a new ADU and found aluminum branch wiring and dry-rotted sill plates where the hillside drainage had wicked moisture for decades. We wrote an allowance for updating the affected circuits and sistering the compromised framing, had the county inspector sign off on the fire-blocking once the wall was open, and kept the ADU on schedule without a single surprise invoice. That is how we handle every Strawberry job. If you are comparing bids, ask each contractor whether their price includes written allowances for wiring remediation and framing repair. If it does not, expect a change order. For an exact quote with these allowances itemized, call (707) 760-0502.
Yes. Strawberry is in a Marin County high-fire-severity zone, and the county enforces California’s Wildland-Urban Interface code on new ADUs and significant remodels. That means ignition-resistant siding, ember-resistant vents, tempered glass on windows facing wildfire-prone vegetation, and documented defensible space. We design these requirements into the plans before submission, so the fire review does not bounce your permit back. Call (707) 760-0502 for a design review that addresses fire compliance on your specific lot.
Usually not, and for good reason. Many 1950s and 1960s Strawberry foundations were built on minimal footings with no seismic reinforcement, and Marin County will not approve a new dwelling on a foundation that predates current code. Reusing an old foundation also limits your floor plan, because the new structure has to fit the old footprint exactly. In most cases, a new poured foundation with proper drainage and seismic ties is the faster and cleaner path. Call (707) 760-0502 and we will tell you honestly whether your existing foundation is worth saving.
It should include line items for site access and slope work, drainage and erosion control, seismic retrofitting, wiring and framing allowances, fire-resistant materials, and the Marin County permit and inspection fees. If any of those are missing from the bid, the contractor is either inexperienced with Strawberry jobs or planning to add costs later. The Kingswell Guarantee means every one of those items is in writing before we start. Call (707) 760-0502 for a free, itemized estimate on your Strawberry ADU.
Written by Russ Delmar, Owner at Lodgewick ADU San Francisco, serving Strawberry since 2010.
