A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateADU Company in Kentfield, CA
Adding an ADU, a room addition, or a full second structure to a Kentfield property is rarely a simple build. The homes here sit on large, estate-style lots, often on hillsides or near the Ross Valley floodplain, and many were custom-built between the 1950s and 1970s. That means plans need real geotechnical input, stormwater management, and materials that can handle wet winters and wildfire exposure. We’re Sutton ADU Builders, and we approach every Kentfield project with a written price before work starts, a 365-Day Done Right Promise, and a crew you’ll know by name and photo before they arrive. Call (831) 272-7212 to talk through your property.
Why Kentfield Homes Are Different
Kentfield’s zoning and terrain separate it from almost every other Marin County town. Many lots are on steep slopes, and the county’s hillside regulations trigger geotechnical reviews that a flat-lot builder would never have to consider. If your property sits near Corte Madera Creek or within the Ross Valley flood zone, the design has to account for significant stormwater runoff and the real possibility of seasonal flooding. Foundation elevations, drainage plans, and retaining walls often become central to the project before a single wall goes up.
The housing stock adds another layer. Kentfield is full of large, architecturally distinct homes built from the 1950s through the 1970s, and most neighborhoods expect new structures to match that character rather than fight it. We regularly work around protected oak trees too. Marin County’s tree ordinances can dictate where a foundation can sit, how high a roof can rise, and whether a detached ADU even fits on a given parcel. None of this is a surprise to us; it’s the normal starting point for Kentfield work.
Our Main Kentfield Services
Most Kentfield homeowners reach out for one of three things: a detached ADU, a home addition that expands the main house, or a room addition that adds usable square footage without a full remodel. Here’s what each looks like on a Kentfield lot.
Home Addition Contractor in Kentfield
A home addition in Kentfield usually means extending the main structure, and that’s where hillside setbacks, protected trees, and flood-zone requirements all come into play at once. We handle the full scope: foundation design, framing, roofing, siding, and interior finish, with James Hardie cladding systems often specified for fire resistance. Every addition gets a written line-item price before we start, and the crew members who show up are background-checked, identity-verified, and photo-badged. See the full breakdown on our Home Addition Contractor in Kentfield page.
ADU Builders in Kentfield
Detached ADUs in Kentfield frequently involve converting an existing detached garage or building a separate backyard structure that respects the main home’s traditional architecture. Prefab and modular lines like Plant Prefab and Boxabl can shorten the timeline, but every site still needs grading, drainage, and foundation work tailored to the slope and soil. We’ll walk you through which product line fits your lot and budget, and the price we give you is the price you pay. Details are on our ADU Builders in Kentfield page.
Room Addition Contractor in Kentfield
A room addition is the smallest of the three, but on a Kentfield hillside it still demands careful foundation and drainage work. Most projects add a bedroom, office, or family room to an existing wing, and matching rooflines and exterior materials matters here more than in most towns. We pull permits, manage inspections, and keep the price fixed from the first written estimate. If something fails within a year, the 365-Day Done Right Promise covers it. Read more on our Room Addition Contractor in Kentfield 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 Kentfield
We have direct experience with Boxabl, Plant Prefab, and James Hardie exterior systems, and we can advise honestly on which fits a Kentfield lot and budget. Tuff Shed conversions are also common here when a garage conversion isn’t viable. See our brands for the full list and what we stock or order for Marin County jobs.
Pricing for ADU Company in Kentfield, CA
| Service | Typical range in Kentfield |
|---|---|
| Detached ADU (500 – 700 sq ft), prefab | $180,000 – $260,000 |
| Detached ADU (500 – 700 sq ft), custom build | $220,000 – $320,000 |
| Garage conversion to ADU | $140,000 – $210,000 |
| Room addition (200 – 400 sq ft) | $90,000 – $160,000 |
| Home addition (400 – 800 sq ft) | $160,000 – $290,000 |
| Tuff Shed conversion to living space | $70,000 – $130,000 |
| Foundation and retaining wall work (sloped lots) | $25,000 – $80,000 |
| Stormwater drainage and site grading | $12,000 – $40,000 |
| Fire-resistant siding and exterior upgrade | $20,000 – $55,000 |
| Protected tree review and design adjustment | $3,000 – $12,000 |
Kentfield prices run higher than flat-lot towns because hillside foundations, drainage, and tree-related design changes add real cost. The number we put in writing before work begins is the number you’ll pay; there are no change orders slipped in silently and no vague allowances that balloon later.
Neighborhoods We Serve in Kentfield
We work throughout Kentfield, from the flatter streets near the creek to the hillside parcels above Sir Francis Drake Boulevard. Response times for estimates are usually within a few business days depending on site access and current permitting queues.
- Kent Woodlands
- Murray Park area
- Corte Madera Creek corridor
- Hillside estates off Crown Road
- Woodside Court and surrounding streets
Service Area – Cities Near Kentfield
Our crews serve Kentfield directly, and we also take on projects in the surrounding Marin and East Bay communities. If you’re in San Anselmo, CA, Fairfax, CA, Novato, CA, or San Pablo, CA, we can schedule a site visit and provide the same written pricing and Threshold Verified crew standards.
Serving Kentfield, CA - Our Local Coverage Area
We’re based in the Kentfield 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 Kentfield
Most Kentfield ADUs take 4 to 8 months from first site visit to completion, but hillside geotechnical reviews and tree ordinance checks can add 4 to 8 weeks before permits are even submitted. Call (831) 272-7212 and we’ll give you a realistic timeline for your specific parcel.
Yes, Marin County permits are required for any ADU, addition, or garage conversion. If your neighborhood has an HOA, its architectural review usually runs parallel to the county process. We pull permits and manage inspections as part of every fixed-price contract.
No. The written price covers the agreed scope, and if site conditions force a change, we discuss it in writing before any extra work happens. The 365-Day Done Right Promise then covers workmanship for a full year. Call (831) 272-7212 for a free estimate.
If you’re considering an ADU, home addition, or room addition in Kentfield, call (831) 272-7212 for a free estimate. We’ll walk the property, explain what your specific lot will require, and put a written price in your hands before you commit to anything.
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 Kentfield Customers Say
"Every crew member was vetted and carried a badge, which matters when they are around your family for months. Tidy site every day."
- Daniel F."Insulated the walls and ceiling properly. It stays comfortable even in July."
- Tamika W."They handled the drawings and the permit paperwork for us. All I had to do was pick the finishes."
- Rosa M.
