Planning, designing and building an Accessory Dwelling Unit (ADU), is similar to the process of building a single-family dwelling, requiring a full set of permits. It is definitely not as simple as building a YardPod or a Shed, which do not normally require permits. Regulations vary defining when a full set of permits are required. Generally, if the building is designed to be lived in and/or plumbing is needed, it will be classed as a habitable unit and it will require permits.
While local regulations and permit fees vary, the basic process is uniform across all jurisdictions. The following is intended to help you to get started.
1 Decide on the Type of ADU which is Right For Your Needs
According to the State of California, an ADU is a secondary dwelling unit with complete independent living facilities for one or more persons and generally takes three forms:
- Detached: The unit is separated from the primary residential structure
- Attached: The unit is attached to the primary residential structure
- Repurposed Existing Space: Space (e.g., master bedroom or garage) within the primary residence is converted into an independent living unit
Accessory Dwelling Units (ADUs) are known by many names: granny flats, in-law units, backyard cottages, secondary units and more. No matter what you call them, ADUs are an innovative, affordable, effective option for adding much-needed housing in California.
Which is right for you?
2 Local Regulations
Once you have decided what type of ADU you would like, before you do anything else, you should visit your local authority Planning & Building Department. Arrange for a meeting at the Department or visit during times that they are available for over the counter discussions. These Departments get very busy, so avoid the earliest times when contractors need to get their questions answered and be prepared to wait.
Most Planning & Building department are extremely helpful to homeowners who visit. They prefer to give advice before any work is done, rather than having to correct mistakes after the fact.
Determine what the local regulations are for where you live.
• Size limitations
• Use limitations
• Parking requirements
Determine a range for the total cost to ensure that you wish to proceed.
Compared to buying a new home, detached ADUs are a very cost effective alternative. Typically 1/2 of a new home. Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo.
- ADU Site Assessment
- ADU Design Drawings
- ADU Construction Drawings
- ADU Permit Fees
- ADU Construction Costs
- Miscellaneous Costs
4 Building Site
Can you build an ADU at your site?
• Do you have sufficient space?
• Do you have good access?
This is where you need professional and independent help, contact us for a Site Evaluation. ADU HQ will submit a report after your Site Assessment with suggestions for location, design concept and potential costs.
Find out about the ADU HQ Site Assessment.
5 ADU Design & ADU Architects/Designers
Select a design professional to work with.
Browse our growing collection of ADU Design Ideas & Inspiration — hand-picked out of thousands for their overall suitability as a Detached ADU.
Ingredients of the ADU Designs in our collection:
- Detached from primary residence
- 1200 sqft or less
- 1-2 Bedrooms
- 1-1.5 Bathrooms
- No basements, converted garages, converted attics, attached add-on units, or houses on wheels
- A mix of low, mid and high cost-to-build designs
Architects & Designers
There are many Architects and Designers available in the SF Bay Area. Some are better than others when it comes to ADUs. When you are searching for an ADU Architect or Designer, consider using this criteria:
- Completed ADU Projects, or previous experience designing similar buildings.
- An active interest in designing ADUs.
- Familiarity with the current ADU Regulations.
- Good reviews on Houzz, Diamond Certified, HomeAdvisor, AngiesList, Yelp, BBB, etc.
6 ADU Builder
Select one or more local ADU Builders.
There are many Builders/GCs available in the SF Bay Area. Some are better than others regarding ADUs. Consider this criteria when are you searching for an ADU Builder:
- Licensed contractor
- Bonded and insured
- Previous experience building detached ADUs
- Good to Great reviews on Houzz, Diamond Certified, HomeAdvisor, AngiesList, Yelp, BBB, etc.
7 Preliminary Cost Estimate
Ask your selected builder(s) for a preliminary estimate.
Work with your design professional or a local architect or design consultant who can prepare a set of Planning and Building permit drawings, specifications, and other required documentation. Have them submitted to the local authority.
9 Firm Price Proposal
Using the permit set of drawings and specification, request firm cost proposals from your selected Builder(s). Proposals should include time estimates to complete the project.
10 Award Contract
Review the Proposal(s). If acceptable, prepare to sign a construction contract once permits are approved. If over-budget, go back to your designer to make modifications and repeat the process. Once permits are approved, sign the contract and schedule a start date.
11 Project Management Assistance (Optional)
Hire your design professional or a project manager to supervise the project.