Building an ADU? Your Insurance May Need to Change.
Accessory Dwelling Units (ADUs) have become one of the most popular ways for California homeowners to add living space, house family members, or generate rental income.
However, one of the biggest mistakes homeowners make is assuming their existing homeowners insurance automatically covers the ADU.
The way an ADU is built—whether it’s attached to the home or detached—can have a major impact on how insurance companies view the risk and how coverage should be structured.
What Is an Attached ADU?
An attached ADU shares at least one wall with the primary residence.
Examples include:
- A room addition with a separate entrance
- A converted section of the home
- An in-law suite
- An apartment built over a garage attached to the home
Attached ADU Example
Because the ADU is physically connected to the main structure, many insurance companies consider it part of the primary dwelling.
How Is an Attached ADU Insured?
In many cases, the ADU is insured under the home’s:
- Coverage A (Dwelling)
- Personal Liability
- Loss of Use
- Personal Property
However, your insurance company will usually want to know:
- Is the ADU owner occupied?
- Is it occupied by family members?
- Is it rented to tenants?
- Is it used as an Airbnb?
The answers can affect eligibility and pricing.
What Is a Detached ADU?
A detached ADU is a separate structure located on the same property but not physically connected to the main home.
Examples include:
- Backyard cottages
- Granny flats
- Converted detached garages
- Stand-alone guest houses
Detached ADU Example
Detached ADUs often require additional attention because many homeowners policies only provide limited coverage for detached structures.
How Is a Detached ADU Insured?
Most homeowners policies automatically include “Other Structures” coverage.
Typically:
- Other Structures Coverage = 10% of Dwelling Coverage
Example
Home Coverage A:
$900,000
Other Structures Coverage:
$90,000
If your detached ADU costs $300,000 to rebuild, the default $90,000 limit may not be enough.
In these situations, your insurance company may need to:
- Increase Other Structures Coverage
- Schedule the ADU separately
- Recalculate replacement cost estimates
- Review rental exposure
Which ADU Creates More Insurance Risk?
Owner-Occupied ADU
Lowest risk:
- Family member occupancy
- Guest house use
- Home office use
Long-Term Rental ADU
Moderate risk:
- Monthly rent
- Tenant occupancy
- Landlord liability exposure
Short-Term Rental ADU
Highest risk:
- Airbnb
- VRBO
- Vacation rentals
Many homeowners policies have restrictions regarding short-term rentals.
Always notify your insurance company before listing an ADU on Airbnb.
ADU Rental Example
Insurance Questions We Ask Every ADU Owner
Before recommending coverage, we typically ask:
✅ Is the ADU attached or detached?
✅ Is it owner occupied?
✅ Is it rented?
✅ Long-term or short-term rental?
✅ What is the square footage?
✅ What was the construction cost?
✅ Does it have a kitchen and bathroom?
✅ Is there a separate address?
These details help determine the proper insurance solution.
Common Insurance Mistakes ADU Owners Make
Not Reporting the ADU
Many homeowners build an ADU and never notify their insurance company.
If a major loss occurs, coverage issues may arise.
Underinsuring Detached Structures
Many homeowners rely solely on standard Other Structures coverage.
This often leaves a significant gap in protection.
Renting Without Proper Coverage
Once rental activity begins, insurance requirements may change.
Skipping Umbrella Coverage
Additional occupants can increase liability exposure.
An umbrella policy may provide valuable protection.
We Help California Homeowners Insure ADUs
Whether your ADU is attached, detached, owner occupied, or rented, it’s important to review your insurance coverage before a loss occurs.
At Starwest Insurance Services, we help homeowners understand how ADUs impact:
- Homeowners Insurance
- Landlord Insurance
- Rental Property Coverage
- Umbrella Insurance
- Liability Protection
- California FAIR Plan Eligibility
Get an ADU Insurance Review Today
Thinking about building an ADU? Already have one on your property?
Let us help you make sure your insurance coverage keeps up with your investment.
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