Vendor Directory
Find your professional team
Our Mission: Helping Homeowners in Napa & Sonoma Build ADUs
One of the most common questions we get is, “Who can help me with my ADU?” To make it easier, we’re continuously adding trusted professionals to the list below who can assist with every stage of your project.
Our Role: Independent, Nonprofit Support for Homeowners
We’re here to help you ask the right questions when choosing your ADU team—like architects, designers, engineers, and contractors. These are the professionals who will help you design, plan, and build your ADU. You’ll hire them directly, but the Napa Sonoma ADU Center is always available to answer questions and offer support as your project moves forward.
The list of industry professionals below is for informational purposes only. Napa Sonoma ADU cannot take responsibility for the services or conduct of any vendor.
Before hiring anyone for your ADU, it’s important to do a little homework. We recommend getting at least three bids from professionals in each category—like designers, engineers, or contractors—so you can compare prices, understand your options, and choose the best fit.
You don’t need to be an expert. Asking questions, taking notes, and trusting your instincts go a long way. Scroll to the bottom of this page for tips and a checklist to help you choose your team. You can also explore the full ADU process in our ADU Workbook.
If you have a negative experience with any of these listed vendors, please let us know at info@napasonomaadu.org.
Finance Professionals
Cross Country Mortgage
ADUloans.net | CrossCountry Mortgage
Loan Officer
- (619) 329-7967
Elisabeth Giron
Searchlight Lending
Oficial de préstamos hipotecarios
Laura Blair
BuildZig Funds Control
Construction Escrow Account Provider
- 800-380-0180
Lindsay Moon
Pro Mortgage
Licensed broker and builder
- 415-819-3794
Provides both traditional and non-traditional financing, e.g. for undocumented, unemployed, self-employed, & other individuals.
RenoFi
Second mortgage Home Equity loans based on the AFTER-construction value of your ADU.
- Loan amounts up to $499,999
- CalHFA $40,000 ADU grant available
Sean Charter
Redwood Credit Union
Assistance Manager – Construction Lending
- 800-609-9009
Our partner on an innovative ADU construction loan product that opens up financing for homeowners who may not be able to qualify for traditional financing. Learn more here & reach out to RCU for a 1:1 consult!
Architects + Designers
Alisa Hofman
Design Set Match
Principal Designer
- 510-285-0870
Design Team with experience in small homes and maximum space use for ADUs.
Nest ADU
Nest ADU
CEO - Builder
- (415) 879-9660
Custom and Prefab ADU Design-Build company. Timeless designs, expertly constructed and delivered fully assembled to your backyard
The Design & Building Works
The Design & Building Works
Designer
- (707) 526 – 9566
Residential design and drafting services specializing in ADUs
The Design & Building Works
The Design & Building Works
Designer
- (707) 526-9566
Whether you’re looking to design and build the dream home you’ve always wanted, create an accessory dwelling unit (ADU) you can rent to help pay your mortgage, need an addition to your home so your elderly parents can come live with you or want the most gorgeous and creative deck in the neighborhood, our drafting service is here to help!
For more resources, please check out our ADU Workbook, including information on how to select a design professional and a useful Initial Design Exercise activity.
Permit Assistance
Keystone Construction Group, Inc.
Preconstruction/Permitting Services
- (707) 365 – 8367
Nest ADU
Nest ADU
CEO - Builder
- (415) 879-9660
Custom and Prefab ADU Design-Build company. Timeless designs, expertly constructed and delivered fully assembled to your backyard
General Contractors + Builders
Gerosa Construction
Gerosa Construction
Founder - GC
- 707-363-5923
North Bay Area builder with several completed ADU projects – from JADU garage conversions, to detached high end homes.
Nest ADU
Nest ADU
CEO - Builder
- (415) 879-9660
Custom and Prefab ADU Design-Build company. Timeless designs, expertly constructed and delivered fully assembled to your backyard
The Design & Building Works
The Design & Building Works
Designer
- (707) 526-9566
Whether you’re looking to design and build the dream home you’ve always wanted, create an accessory dwelling unit (ADU) you can rent to help pay your mortgage, need an addition to your home so your elderly parents can come live with you or want the most gorgeous and creative deck in the neighborhood, our drafting service is here to help!
For more guidance on how to choose a general contractor, please visit our Construction page and our ADU Workbook.
Prefab Builders
Cassette Systems
Cassette Systems
Prefab Builder
- 310-402-2404
Architecturally designed. modular ADUs. Seven modules to choose from and connect in various configurations.
Nest ADU
Nest ADU
CEO - Builder
- (415) 879-9660
Custom and Prefab ADU Design-Build company. Timeless designs, expertly constructed and delivered fully assembled to your backyard
See more about traditional vs. prefab construction on our ADU 101 page, our Getting Started page, and our ADU Workbook.
Geotechnical Engineers
Engineers
More Professionals
The professionals on this list work in both Napa and Sonoma counties and perform site evaluations and design alternative sewer disposal systems. They may offer various other services including geotechnical analysis, septic analysis, surveying, civil engineering, etc.
The professionals on this list are qualified septic consultants.
Title 24 / CalGreen Energy Consultants
A Title 24/CalGreen Energy consultant is a specialist who analyzes architectural plans to ensure they comply with Title 24, the code section that deals with energy efficiency, and CalGreen, the “green building code.”
Typically the designer/architect will handle the relationship with the Title 24/CalGreen consultant. There may be 1 or 2 rounds of finessing the design to make it comply before it can be submitted to the jurisdiction for approval. Check out our ADU Workbook for more information on Title 24.
Some jurisdictions require that homeowners select a consultant from their list of approved vendors, including the City of Santa Rosa, Sonoma County, and City of Sonoma. Those lists of consultants, who can also work in other jurisdictions, are included here:
City of Santa Rosa Approved CALGreen Inspector List (last updated September 2020)
County of Sonoma | Permit Sonoma CALGreen Special Inspection Agency Recognition List (last updated November 2020)
City of Sonoma Authorized Special Inspection Companies (Category #11) (last updated October 2020)
Additional Resources for Hiring Vendors
CA Department of Consumer Affairs California Architects Board Consumer’s Guide to Hiring an Architect
CA Department of Consumer Affairs Consumer’s Guide to Hiring a Landscape Architect
CA Department of Consumer Affairs Contractors State License Board: Information on the status of a contractor’s license and tips on hiring a builder
CA Department of Consumer Affairs Consumer Guide to Engineering and Land Surveying (including hiring an engineer or land surveyor)
CA Public Utilities Commission (CPUC) California Solar Consumer Protection Guide
The Down-Low on a Special Kind of ADU: Junior Accessory Dwelling Units (JADUs)
Welcome to the Napa Sonoma ADU Center! Learn more about us →
Watch our Calistoga ADU Webinar!
Sign up for an ADU Feasibility Consult!
Napa Sonoma ADU in the News: New director leads center to promote Napa accessory dwelling units
