Building an accessory dwelling unit (ADU) adds significant value to your property, but standard homeowners insurance usually isn't enough to protect it. Many homeowners assume their existing policy automatically covers a new build. In reality, renting it out or exceeding baseline property limits can void your coverage during a claim. The right protection depends on how the space is used.
Do you need a separate insurance policy for an ADU?
Whether you need a separate policy or just an endorsement depends on who lives in the unit. Figuring out how to insure an accessory dwelling unit comes down to three distinct use cases:
1. Personal Use (Family, Guests, or Home Office)
The Standard Coverage: If the unit is used by family members (often called granny flat insurance or casita insurance), it generally falls under your primary homeowners policy (HO-3).
The Coverage B Gap: Standard policies allocate "Other Structures" (Coverage B) at 10% of your primary dwelling limit (Coverage A).
Example: If your main house is insured for $500,000, your ADU is only covered up to $50,000. With 2026–2027 rebuild costs averaging $250-400 per square foot, a $150,000 ADU leaves you underinsured by $100,000.1
2. Long-Term Renters (Income Property)
The moment you collect rent from a non-relative, your standard homeowners policy will likely exclude coverage for the ADU. You need a DP-3 policy, commonly known as ADU landlord insurance. This covers the structure, landlord liability, and loss of rental income if the unit becomes uninhabitable.
3. Airbnb and Vrbo (Short-Term Rentals)
Most standard landlord (DP-3) policies explicitly exclude short-term rental activity. Instead, specialized short-term rental insurance is required for guest house setups or a commercial rider attached to your policy.
H2: Comparing Coverage: HO-3 vs. DP-3 Landlord Policy
Feature | Standard Homeowners (HO-3) | Landlord Policy (DP-3) |
Primary Use Case | Family members, personal use | Paying tenants (long-term) |
Structure Coverage | Limited to Coverage B (usually 10%) | Insured to full 2026 replacement cost |
Liability Coverage | Covers family/guest injuries | Covers tenant-related lawsuits |
Loss of Rent Income | ❌ Not included | ✅ Included (typically up to 12 months) |
Tenant's Belongings | ❌ Not included | ❌ Not included (Requires Renters Insurance) |
How Dedicated Rental Insurers like Steadily Qualify ADUs
Standard homeowners policies often struggle with non-traditional structures. Specialized landlord insurance platforms like Steadily cater specifically to rented ADUs, but they enforce strict eligibility criteria:
Supported Structure Types: Detached backyard cottages, converted garages, and attached additions.
The "Self-Containment" Requirement: The ADU must be a fully self-contained unit with its own private kitchen, bathroom, and living space.
The Rental Mandate: Coverage only applies if the ADU is actively rented to a third party.
Allowed Setup: Owner lives in the main house and rents out the ADU.
Excluded Setup: Owner lives in the ADU (even if renting out the main house)—coverage will not apply.
Coverage Boundary: Protection is strictly limited to activities occurring inside the ADU, even though the owner shares the same property lot.
Renting out your backyard cottage or converted garage? Check your eligibility with a SelectQuote licensed insurance agent to see if Steadily is right for you.
Expected ADU Insurance Costs (2026-2027 Estimates)
Understanding expected premiums helps ensure you build an accurate budget before construction or leasing begins:
Homeowners Endorsement (Personal Use): Typically adds $300 to $800 per year to increase Coverage B limits to the proper rebuild value.1
Standalone Landlord Policy (DP-3): Averages $1,200 to $1,895 per year, depending on geographic risk (e.g., wildfire zones or coastal regions).1
Builder's Risk (During Construction): A six-month Course of Construction policy usually costs $500 to $1,500 to protect materials and the unfinished structure from theft or fire.1
Insurance rates vary by zip code and structure type. Get a free, custom quote today to see your exact premiums.
Three Critical Insurance Mistakes ADU Owners Make
Skipping the Umbrella Policy: If a tenant's guest is severely injured, your $300,000 landlord liability limit can be exhausted quickly. A $1 million to $2 million umbrella policy protects your primary assets and costs just $150 to $400 per year.1
Insuring to Appraised Value Instead of Rebuild Cost: Inflation has shifted construction economics. Always insure to the 2026 local replacement cost, not the tax-assessed or market appraisal value.
Not Requiring Renters Insurance: Your ADU insurance does not cover a tenant’s stolen laptop or ruined furniture. Mandating a $100,000 renter's liability policy in your lease agreement offers additional protection and peace of mind.
Secure the Right Protection for Your ADU Today
Don't wait until a fire or a tenant lawsuit to find out your standard homeowners policy has a massive coverage gap. If you currently have an ADU or are considering adding one, call one of our licensed agents and they can recommend a policy that would best fit your needs. Whether it's a backyard casita for family or a high-yield rental unit, your property needs accurate, updated protection.
Rebuild cost ranges are estimated based on 2026–2027 national construction benchmarks, general contractor market data, and regional residential replacement cost indicators. Actual ADU construction and insurance costs vary significantly depending on structure type (detached vs. garage conversion), square footage, local labor rates, material quality, utility line tie-ins, and local geographic risk factors (such as wildfire or coastal zones). These figures are provided for general educational purposes and do not represent a guaranteed quote. To determine exact replacement costs and coverage needs for your specific property, consult with a licensed SelectQuote insurance agent.
