Help comes for the California Wine Country housing shortage: How to build accessory dwelling units

Napa Sonoma ADU Center

3299 Claremont Way, Suite 2, Napa, CA 94558;; 707-804-8575

Upcoming webinars

Oct. 28 : ADUs 101 for Napa and Sonoma County Homeowners, 6–7:30 p.m.

Nov. 12: How to Build an ADU in unincorporated Sonoma County in collaboration with Permit Sonoma, 6–7:30 p.m.

Creating a new home where there’s already a single-family residence, whether by converting a garage into a living space or constructing a separate “granny “unit on the same property, is a rising answer for some to the housing shortage.

Now a nonprofit center has been set up to provide free help in how to get started, including financial planning, budgeting, permitting, design considerations and construction tips for accessory dwelling units (ADU) in Napa and Sonoma counties.

The nonprofit Napa Sonoma ADU Center’s advisers and partners track frequently changing state and local ADU laws and policies, conduct focus groups and interviews with local homeowners. It also provides a step-by-step ADU workbook, created by Baird + Driskell Community Planning, offering useful information and reduce the uncertainty in what many feel is a complicated process, among other vital services.

Established in late Spring 2020, the center is a fiscally-sponsored project of Napa Valley Community Foundation with support from Community Foundation of Sonoma County and from the cities of Napa and Calistoga as well as Napa County which have collectively provided $350,000 for the budget.

“I believe in a future where every person in Napa and Sonoma can afford to live and thrive here. ADUs can help bridge the middle-income housing gap and can contribute significant housing production relatively quickly and affordably with opportunities to expand access to lower income households,” said ADU center Director Renee Schomp, a native of Sonoma County.

She has worked as an attorney focusing on civil legal aid and as a nonprofit leader. Schomp and her husband live in an above-garage ADU in West Sonoma County.

She said the ADU center collaborates with the 16 local municipalities and jurisdictions, nonprofits and the private sector with a goal of increasing housing affordability in the community. To date, the center has completed 13 ADU feasibility Reports, with 15 more currently in the pipeline, while also helping more than 70 homeowners with their ADU questions. Seven hundred interested homeowners have signed up for the center’s newsletter and 435 have registered to participate in the ADU center’s initial five ADU webinars.

With the housing shortage a statewide concern, Schomp said homeowners are thinking about having the flexibility to age in place or possibly downsize, while providing space for extended family and friends, or having room for grown children returning home. As a result, an increasing number are weighing options for building ADUs – while also thinking about having rental income to help pay bills or the mortgage.

Since 2014, a total of 1,026 ADUs have received building permits across both Napa and Sonoma counties through 2019. In Sonoma County, 823 ADUs were permitted during the six-year period from 2014 to 2019, according to data from the California Department of Housing and Community Development.

Some 70% of completed ADUs involve detached units, 9% are attached and 23% are built above existing garages.

How much will it cost?

Cost is a major factor. According to the ADU Center, the typical hard construction cost for an ADU is between $325 and $425 per square foot, in addition to the soft costs of design and permitting. Schomp recommends that interested parties should meet first with their local planning division before having plans drawn by a professional designer or architect to avoid costly revisions.

Construction costs vary depending upon the type of ADU involved. For small internal conversions within existing homes, costs can be under $55,000. For attic and basement conversions, the cost can range from $80,000 to $150,000, and garage conversions can vary from $80,000 to $200,000 (with a maximum of 400 square feet). For attached ADUs, the cost can be from $170,000 to $250,000 and up, and for detached ADUs, costs can range from $170,000 to $400,000 and up.

How soon can a homeowner see an ROI on an ADU?

When calculating a homeowner’s ADU return on investment, this can take from one to nine years, depending on size and costs. This outcome can be addressed by using the ADU calculator on the center’s website.

The timeline for ADU completion typically takes between 6 months to two years from the start of design through occupancy

Schomp said under a new state law, ADU permitting timeline has been reduced to no more than 60 days, and sometimes even less, if applications are complete. She added that garage and home conversions are relatively easy if the homeowner is converting already-finished space.

Praise from government

Officials in the public sector who focus on housing issues were happy to see the Napa Sonoma ADU Center get up and running.

Napa Sonoma ADU Center

3299 Claremont Way, Suite 2, Napa, CA 94558;; 707-804-8575

Upcoming webinars

Oct. 28 : ADUs 101 for Napa and Sonoma County Homeowners, 6–7:30 p.m.

Nov. 12: How to Build an ADU in unincorporated Sonoma County in collaboration with Permit Sonoma, 6–7:30 p.m.

“We are working with the ADU center on a program that will include a user friendly ADU permit guide,” said Katrina Braehmer, a planner in the project review division of Permit Sonoma who believes the ADU center is a third-party resource for property owners.

“Renee and her team are a helpful information resource about Sonoma County standards and regulations. Another project in the works will add pre-approved ADU plans that can be purchased at a lower cost so homeowners don’t have to hire an architect if they choose this option. Details about these new programs will be announced soon,” Braehmer added.

Jesse Oswald, chief building official with the city of Santa Rosa, said the ADU Center not only answers homeowner questions, it reduces the fear factor laypersons may have by offering one-on-one quality time with subject matter experts who can explain things without the use of building jargon while developing a building roadmap. The center also assists the public in fine-tuning permit applications improving chances they will receive approvals quickly.”

He said while state law requires action and reviewing permit applications within 60 days, Santa Rosa typically turns this phase around within 30 to 45 days.

“Ten years ago, impact fees for new construction ranged between $10,000 and $20,000. Now there are no entitlement fees for ADUs under 750 square feet, just those associated with design reviews and plan checks,” Oswald added.

Napa Sonoma ADU Center tools and resources

ADU calculator: Helps homeowners estimate the costs, returns and benefits associated with building an ADU.

Municipal rules: Lists of city and unincorporated area standards for ADUs in Napa and Sonoma counties are provided and kept up to date with revisions that reflect new state laws.

Address look-up tool: Helps to determine if you can build an ADU on your property.

ADU workbook: Aids homeowners in Napa and Sonoma Counties through ADU planning, designing and permitting information and worksheets, as well as the rental process.

Stories and floor plans: Experiences of five homeowners with ADUs, where you can find inspiration from neighbors’ ADU plans.

Vendor registry: Currently under development, will list builders, designers, architects, prefab companies and others as a resource for homeowners.

Newsletter and social media: Share updates and information about ADU news.

High-level assistance: Problem solving by phone or email to answer ADU questions based on liaisons with planning and building divisions in 16 jurisdictions across Napa and Sonoma counties.

Advocates, users praise idea

According to Robin Stephani, president of 8th Wave, current chair of the Sonoma County Alliance Housing Task Force and a founding member of Urban Community Partnership, “I believe the ADU Center is well organized and positioned to offer homeowners a high-level advisory service on the ADU building process, can assist them in investigating possibilities and help them learn how to launch their projects. Having a resource advocate on your side is a good way to begin.”

For Larry Florin, president and CEO of Burbank Housing, and a member of the ADU Center advisory committee, “This center’s approach is another tool to ease pressure caused by a lack of housing and is part of an overall solution to encourage more home construction. Sacramento has changed its laws making it easier to build ADUs, and now financing these units is starting to come into focus as well.

Many homeowners who have worked with ADU Center’s consultants are pleased with the results.

“I did not know where or how to start,” said Jacqueline Pio Roda, a Realtor and property owner with a home near the Silverado Country Club in Napa. She began her ADU journey by completing a short, ten-minute ADU Center questionnaire.

Scott Johnson, an ADU expert who works as a consultant with the ADU Center, conducted pre-screening research on her parcel, followed by a one-hour socially-distanced site visit. He then prepared a detailed, 20-page feasibility report outlining options to help her navigate her ADU buildout. Johnson is the founder of the ADU consulting firm Pocket Housing.

"I’m impressed with the well-thought-out report customized to fit my needs based on my feedback to the ADU consultant,” Pio Roda said. “I am now able to identify the components needed to build an ADU, can weigh the pros and cons of ADU options and can make informed decisions based on that. I was also given a clear view of timing and next steps which is very helpful."

Ethan Hare, principal with Hare Construction with offices in Monterrey and Napa, is the contractor selected to build Pio Roda’s ADU. He has built ADUs in Monterrey’s Pacific Grove, San Francisco and three in Napa.

“It’s often not easy for members of the public to communicate with planning and building department personnel who may use unfamiliar terms and language. Consequently, having an ADU Center takes the burden off building divisions while providing homeowners with a trusted way to learn where to begin, the order of operations and who to speak with, and the right questions to ask. Simplifying the entire process makes development more understandable.”

Show Comment

Our Network

The Press Democrat
Sonoma Index-Tribune
Petaluma Argus Courier
North Bay Business Journal
Sonoma Magazine
Bite Club Eats
La Prensa Sonoma
Sonoma County Gazette