Casita and Garage Conversion Insurance: What Your Policy Needs to Know
Casita and garage conversion insurance is one of the most overlooked steps in a home improvement project. You pull the permits. An inspector signs off. Crews finish the work correctly. Then the policy quietly keeps describing a property that stopped existing the day the project finished. Nobody at the building department tells you to call your agent, so the call never happens.
What counts as added living space?
Homeowners add living space in two common ways. You build something separate in the backyard. Or you take space inside the house and finish it into an apartment.
The first is usually called a casita, a guest house, or a backyard cottage. The second is most often a garage conversion. Local governments call both of them accessory dwelling units, or ADUs. Almost nobody uses that term out loud.
The label does not matter much. What matters is one physical fact: is the new space attached to your house, or detached from it? That single question sends the two projects down different paths in your homeowners policy.
Why attached and detached follow different rules
A standard homeowners policy splits property coverage into parts. Coverage A is the dwelling. Other structures fall under Coverage B. Your belongings fall under Coverage C.
A detached casita is a separate building on your lot. It lands under Coverage B. An attached garage was already part of the house, so a conversion stays under Coverage A.
Structures connected to the dwelling by only a fence, a utility line, or a similar connection still count as detached on most forms. A shared wall or a covered walkway usually makes a structure part of the dwelling instead.
How a detached casita is covered
Coverage B is rarely a number someone picked for your property. Many policies default it to a percentage of your dwelling limit. Ten percent is common, though it varies by carrier and by form.
A home insured for $600,000 would carry roughly $60,000 in other structures coverage at that default. Everything detached shares that amount. Your fence, your shed, your detached garage, and your casita all draw from the same limit.
Now compare that to what a casita costs. Angi data cited by Mercury Insurance puts the typical ADU range between $60,000 and $225,000. Nobody sized that default limit for a second dwelling. It covers a shed and a fence.
Raising the limit
Most carriers will increase an other structures limit. Some let you raise the percentage. Others will schedule the structure specifically. According to MoneyGeek, the premium change for a higher Coverage B limit is often just a few dollars a month.
You have to ask for it. Nothing about the project triggers the change on its own.
How a garage conversion is covered
A converted attached garage does not go to other structures at all. You did not add a detached building. The space stays under your dwelling limit.
That sounds simpler. The number underneath it still changed.
Your dwelling limit reflects what it would cost to rebuild your home as it sits. Carriers estimate that from the characteristics of the house, and square footage is one of the biggest inputs. So is what that square footage actually is.
A garage and a finished living space are not the same thing to rebuild. Your garage was a slab, framing, a door, and often unfinished walls. That conversion added insulation, finished walls and flooring, electrical, likely plumbing, heating and cooling, and sometimes a full bathroom.
The footprint may be identical. Rebuilding that square footage costs far more.
If your carrier still values that space as a garage, your dwelling limit reflects a house that no longer exists. On a total loss, the entire rebuild runs against a limit calculated on the wrong house.
What about extended replacement cost?
Some policies carry extended or replacement cost provisions that add a cushion above the stated limit. Those help. They also usually run as a percentage cushion, calculated from the same understated number. That cushion absorbs a construction cost spike, not a room nobody counted.
Coverage response by project type
| Project | Which coverage responds | The common gap | What to ask for |
|---|---|---|---|
| Detached casita or backyard cottage | Coverage B, other structures | Default percentage limit sized for a shed, and shared with fences and sheds | Increase the other structures limit or schedule the structure |
| Attached garage converted to living space | Coverage A, dwelling | Dwelling limit still reflects garage construction, not finished living space | Have the replacement cost estimate rebuilt around the current house |
| Belongings inside either space | Coverage C, personal property | Property owned by a non-household occupant may not be covered | Confirm whose property is there, and have a tenant carry renters coverage |
| Either space rented to a tenant | Varies. May move off the homeowners form | Rental use can remove a detached structure from other structures eligibility | Ask whether an endorsement fits or a different form is required |
| Either space used for business | Generally excluded from the homeowners form | Business-use structures are commonly excluded outright | In-home business endorsement or a commercial policy |
What changes when someone moves in
Limits are only half the question. The other half is who occupies the space.
Family staying in a casita is one situation. A tenant paying rent is a different one. Once rent enters the picture, you have added a business activity to a residential property.
This matters more than most homeowners expect. On standard forms, other structures coverage does not extend to structures rented or held for rental to someone who is not a tenant of the dwelling. MoneyGeek notes that rental use, including occasional short-term rental, can remove a detached structure from Coverage B eligibility entirely.
So raising your other structures limit solves the wrong problem if the casita has become a rental. The structure may no longer sit in that coverage part at all.
Carriers underwrite an owner-occupied home differently than a home with a rental unit. Some will endorse the homeowners policy to handle one rental unit on the property. Some want the risk written on a different form. For a detached unit with separate utilities functioning as a rental, a landlord or dwelling fire policy is sometimes the better fit.
This runs both directions. If your in-laws move out and you rent the casita, the situation changed even though the building did not. If a garage rental becomes a home office or a space for family, that changed too.
Occupancy and how the policy responds
| Who occupies the space | Typical treatment | What to confirm with your agent |
|---|---|---|
| You or a household family member | Generally stays within the homeowners form | That limits match what the finished space costs to rebuild |
| A relative who is not part of your household | Structure usually still covered. Their belongings may not be | Whose personal property is in the unit, and who insures it |
| A long-term tenant paying rent | May require an endorsement or a different policy form | Whether your carrier will write it, and on what form |
| Short-term or vacation rental guests | Commonly restricted or excluded on standard forms | Whether any short-term rental activity is permitted at all |
| A business, client, or workspace use | Generally excluded from the homeowners form | Whether an in-home business endorsement or commercial policy applies |
What about during construction?
A homeowners policy may provide some coverage while work is underway. It was not necessarily priced or underwritten for a major construction project.
During the build you have materials on the property, crews coming and going, and a partially finished structure exposed in ways a completed one is not. How much of that your policy picks up varies by carrier and form. Some carriers want to know about a project of any real size before it starts.
Your contractor’s insurance matters here too. Verify their license. Ask for a certificate of insurance. Check that they carry general liability, and workers’ compensation if they have employees. An uninsured contractor can leave you facing the claim yourself when someone gets hurt.
Does my policy cover the contents of the unit?
Personal property is Coverage C. It follows you and your household, and it assumes your things sit inside your house.
Contents inside a detached structure fall under Coverage C, not Coverage B. Coverage B protects the structure itself and its permanent fixtures.
If the property in the casita belongs to a household relative, that is usually one answer. For an occupant outside your household, do not assume their property qualifies. A tenant’s belongings generally fall outside your policy entirely. That is what renters insurance handles, and a tenant in that unit should carry it.
Do I need to tell my insurer if I pulled permits?
Yes, and the permits are not the reason.
Permitting is a building department matter. Your homeowners policy is a separate contract with a separate company. Passing a final inspection does not notify your carrier that the property changed.
Your carrier needs the updated picture of the property: what you added, how big it is, how you use it, and who lives in it. Limits and forms follow from that picture.
What does the coverage change cost?
Two different numbers matter here, and they are worth separating.
The project itself is the large one. Angi figures cited by Mercury Insurance put typical ADU construction between $60,000 and $225,000, depending on size, type, and finish. Garage conversions generally sit at the lower end of that range.
The insurance adjustment is the small one. MoneyGeek reports that increasing a Coverage B limit through an endorsement typically raises premium by a few dollars a month, which makes it one of the more cost-effective coverage changes available. Adjusting a dwelling limit to reflect finished living space will move premium more, because the replacement cost basis genuinely changed.
Pricing varies by carrier, state, and property. There is also a return side worth noting. The National Association of Realtors, also cited by Mercury, found homes with an ADU priced about 35 percent higher on average than comparable homes without one.
Who should make this call?
Anyone planning a casita, a backyard cottage, a garage conversion, or any project that adds finished living space to a residential property.
Make the call before you break ground. Your agent can tell you what the finished project does to your limits, and whether your current carrier wants the risk at all. That is worth knowing while you still have options.
If the project is already done, the call is still worth making. Updating a policy to match the property is routine work.
Frequently asked questions
Is a casita covered under my homeowners policy?
A detached casita is generally covered under Coverage B, other structures, on a standard homeowners policy. The common problem is the limit rather than the coverage. Coverage B is often defaulted to a percentage of your dwelling limit, and that default is rarely enough to rebuild a second dwelling.
Does converting my garage change my homeowners insurance?
It should. The converted space stays under your dwelling coverage because it attaches to the house, but the cost to rebuild it changed substantially. If the carrier still values that area as garage space, your dwelling limit reflects a house that no longer matches the property.
What happens if I rent out my casita?
Rental use changes the structure’s classification. On standard forms, other structures coverage does not extend to structures rented or held for rental to someone who is not a tenant of the dwelling. Depending on the carrier, that may mean an endorsement, or the unit may need a different policy form.
Does my tenant need their own insurance?
Yes. Your policy covers your property, not theirs. A tenant living in a casita or a converted unit should carry a renters policy for their own belongings and liability.
Do I need to tell my insurance company about an ADU?
Yes. Different organizations handle building permits and insurance policies, and they do not share information. Your carrier only knows what you tell them, and limits follow from the picture of the property on file.
Is a detached casita covered for flood or earthquake damage?
Generally no. Flood and earth movement exclusions apply across a standard homeowners policy, including other structures. Those perils require separate flood or earthquake coverage.
Talk it through before the project, not after
Western Pacific Insurance is an independent agency. We write homeowners coverage in Nevada, Arizona, Utah, and California, and we shop multiple carriers to find the fit for your property and your state.
If you are planning a casita or a garage conversion, or you already finished one, we can look at what your policy actually says about it. Get a quote or reach out and we will walk through it with you.
Learn more about coverage in your state: Nevada, Arizona, Utah, and California.
