Buying a San Ramon Home With an ADU? 8 Things to Verify Before You Make an Offer
A home with an accessory dwelling unit (ADU) can offer flexibility: extra living space, a separate area for guests, or the possibility of accommodating changing household needs. But before buying a San Ramon property with a backyard cottage, converted garage, or attached secondary unit, make sure you understand what has actually been built and approved.
A finished-looking unit is not proof that it has the required permits or final approvals. Reviewing the records before you commit can help you assess the property's condition, practical usefulness, and potential costs.
Quick Answer: What Should You Check Before Buying a San Ramon Home With an ADU?
Verify the ADU's permit history, approved plans, inspection records, utility arrangements, access, and any property-specific restrictions. Compare what exists on-site with what the City of San Ramon has approved, and investigate differences before your purchase deadlines expire.
Start with the City of San Ramon's official ADU information and its permit and plan submittal resources. For questions about a particular property, contact the city directly rather than assuming that general ADU rules establish the property's compliance.
1. Confirm the Unit's Permit History
Ask for documentation showing what was approved, what was constructed, and whether the required approvals were completed. An ADU may look like a separate apartment but have a different legal or permit status than you expect.
Request available building permits, approved plans, inspection records, and final sign-off documentation. If the seller cannot provide them, ask the city what records are available and whether additional research is necessary.
The City of San Ramon maintains an ADU application process and publishes information about ADU requirements. California's Department of Housing and Community Development also provides an ADU Handbook, updated in March 2026, explaining California's ADU laws.
Pay particular attention if the property includes:
A garage converted into living space.
A detached backyard cottage.
A room addition with a kitchen or bathroom.
A unit described in marketing materials as a separate residence.
Do not assume that a seller's description, previous use, or the presence of appliances establishes that the unit is legally approved for its current use.
2. Compare the Approved Plans With the Actual Unit
Even when permits exist, the finished structure may differ from the approved plans. Look at the unit's layout, approximate size, doors and windows, kitchen and bathroom areas, and its location relative to the main home.
Ask the seller for approved plans and compare them with the existing construction. If there are apparent differences, request clarification from the city and the appropriate building professional.
Questions worth investigating include:
Was the garage conversion included in the approved plans?
Were additional rooms or bathrooms added later?
Does the existing layout match the permitted configuration?
Are there inspection records for relevant construction work?
Are there unresolved permit items?
A difference does not automatically mean that the work is unlawful or impossible to correct. It does mean you should understand the issue, potential remedies, and cost implications before deciding how to proceed.
3. Understand What the ADU Can Legally Be Used For
An accessory dwelling unit is generally a secondary residential unit on a property that also contains a primary dwelling. A junior accessory dwelling unit (JADU) is a separate category under California law; state law generally defines it as a unit of no more than 500 square feet contained entirely within an existing or proposed single-family residence.
The applicable rules can differ depending on the type of unit, its location, the property, and the relevant law. Do not assume that every space described as a guesthouse, in-law unit, or converted garage qualifies as an approved ADU or JADU.
If you intend to use the space for a specific purpose, verify that the unit's approval and applicable requirements support that use. The California HCD ADU Handbook is a useful starting point, but property-specific questions should be directed to the city and qualified professionals.
4. Check Utilities, Access, and Practical Functionality
A secondary unit's usefulness depends on more than its interior appearance. Investigate how it receives electricity, water, sewer service, and other utilities, and whether the arrangement meets applicable requirements.
Ask for available documentation about utility connections and any relevant work performed. During inspections, look for visible signs of moisture, drainage problems, damaged finishes, and other concerns, while recognizing that a general home inspection may not answer every specialized question.
Also evaluate the physical layout:
Is there a practical way to reach the unit?
Are exterior doors, pathways, and stairs in suitable condition?
Is parking available where needed and permitted?
Could landscaping, drainage, or retaining walls affect access?
Are there shared utility or maintenance arrangements that need clarification?
These questions matter whether you plan to use the ADU for guests, extended household needs, or another permitted residential purpose.
5. Review Easements, Lot Layout, and Property Restrictions
An ADU's location can matter just as much as its interior. Review available parcel information, the preliminary title report, and relevant recorded documents for easements or other restrictions that may affect the structure or future improvements.
The City of San Ramon specifically notes that detached ADUs under its permit-ready program cannot be located within an easement. That requirement is a reason to investigate the actual location of an existing unit rather than assume that a structure's presence establishes that its placement is acceptable.
Start with the city's ADU program and application information. If the boundary or location of an easement is unclear, consult the appropriate professionals, including a qualified land surveyor when exact boundary information is needed.
Do not assume every easement prohibits every improvement. The effect depends on the recorded terms, applicable rules, and property-specific circumstances.
6. Calculate the Real Ownership Costs
An ADU may add useful space, but it can also come with expenses beyond the purchase price. Build a realistic budget based on the actual property rather than assuming the unit is ready to use without further spending.
Consider potential costs for:
Repairs or deferred maintenance.
Corrections to documented construction or permit issues.
Utility work or service upgrades.
Insurance review and any applicable policy changes.
Ongoing maintenance for the main home and secondary unit.
Professional inspections, records research, or legal advice.
Ask your insurance provider whether the existing policy covers the structure and your intended use. If you need a mortgage, discuss the property configuration and any unresolved permit questions with your lender early. Do not assume that an ADU will automatically increase the appraised value by a particular amount or that every lender will evaluate it the same way.
7. Evaluate Any Financial Benefit Conservatively
If you are considering a property partly because of the ADU's potential financial contribution, distinguish documented facts from assumptions. Verify the unit's legal status, expected expenses, and intended use before incorporating any projected income into your affordability calculations.
Avoid relying solely on a listing description or a seller's estimate of potential earnings. If you intend to use the unit in a way that involves rental activity, independently confirm the applicable legal, tax, insurance, and financing requirements. The key purchase question remains whether the property and its approved configuration fit your plans and budget.
8. Investigate Questions Before Your Contract Deadlines
If you discover missing records, inconsistent plans, or possible unpermitted work, raise the issue promptly. Ask your agent to help coordinate the relevant questions, request available seller documentation, and identify which specialists may be needed.
Depending on the issue, that could mean contacting the city, arranging a specialized inspection, consulting a contractor, or obtaining advice from a California real estate attorney. The appropriate next step depends on the facts.
Your rights and options are governed by your purchase agreement and applicable law. Do not assume that a concern automatically allows you to cancel, extend a deadline, or require the seller to make repairs. Review the contract and seek appropriate professional advice before making a decision.
Agent's Insight: Waleed "Walter" Akbar's Local Perspective
When evaluating a San Ramon home with an ADU, I recommend separating three questions: Does the space meet your needs? Do the available records support its status and configuration? And does the total ownership cost fit your plan?
A property can be attractive while still requiring additional research. Addressing important questions before your contractual deadlines gives you a clearer basis for comparing homes and deciding how to proceed.
San Ramon ADU Homebuyer Checklist
Before moving forward, consider whether you have:
Requested available permits, approved plans, and inspection records.
Compared the existing unit with the available plans.
Confirmed the unit's status and intended use with the appropriate authorities.
Reviewed utility arrangements, access, and physical condition.
Examined relevant title documents and easements.
Asked your insurer and lender about property-specific requirements.
Budgeted for repairs, maintenance, and professional advice where needed.
Reviewed purchase-contract deadlines and options with the appropriate professionals.
Frequently Asked Questions
Does a San Ramon home with a finished backyard unit automatically have a legal ADU?
No. Appearance and previous use do not establish permit status. Request documentation and verify the property's records with the City of San Ramon.
Can I buy a home if the ADU has missing permits?
A missing record does not, by itself, answer whether the purchase is appropriate or whether the issue can be resolved. Investigate the unit's status, possible corrective steps, costs, and your contractual options before proceeding.
Does an ADU automatically increase a home's value?
No specific increase should be assumed. Value depends on the property, the unit's condition and approval status, buyer demand, and how the appraiser and market evaluate the feature.
Where can I find San Ramon's ADU requirements?
Start with the City of San Ramon's ADU webpage. For state-level guidance, consult the California HCD ADU Handbook.
Should I hire a specialist to inspect an ADU?
Consider specialized help when the unit has unclear permits, apparent construction differences, utility concerns, or other issues beyond a standard home inspection. The appropriate professional depends on the question being investigated.
Buying a Home in San Ramon? Get a Clearer Picture Before You Offer
An accessory dwelling unit can be an important part of your home search, but the right decision requires more than counting bedrooms or looking at finished square footage. Confirm the documentation, investigate anything unclear, and evaluate the property against your actual plans.
For personalized guidance buying or selling a home in San Ramon, Danville, Dublin, Walnut Creek, Alamo, Pleasanton, or Livermore, contact Waleed "Walter" Akbar at (510) 541-1610. Visit walterakbar.com to discuss your buying strategy.