Key Takeaways
- Attached structures like a built-in garage or deck are covered under Coverage A — your dwelling coverage.
- Detached structures fall under Coverage B (Other Structures), which defaults to just 10% of your dwelling limit.
- Fences, driveways, and sheds all count as other structures — and that 10% cap can run out fast.
- Replacement cost vs. actual cash value matters enormously for detached garages and older outbuildings.
- Some structures — like those used for business or rented out — may be partially or fully excluded from Coverage B.
Our Verdict
Attached structures get the full weight of your dwelling coverage behind them. Detached structures do not — they're capped at a separate sub-limit that most homeowners never think to adjust until they file a claim. If you have a detached garage, a substantial fence, or any outbuilding worth replacing, the default 10% Coverage B limit almost certainly isn't enough. Review your policy, price out what replacement actually costs, and buy up coverage B if needed.
| Best for | Recommended |
|---|---|
| Homeowners with only an attached garage and a basic wood fence | Default Coverage A + Coverage B at 10% |
| Homeowners with a detached garage, barn, or substantial outbuilding | Increased Coverage B limit or separate structure endorsement |
| Those with a pool house, studio, or structure used for any business purpose | Dedicated endorsement or standalone policy for business-use structures |
| Investors or owners who rent out a guest cottage or ADU | Landlord policy or scheduled structure coverage |
Why the Attachment Question Matters More Than You Think
When homeowners hear the word "coverage," most picture the house itself — four walls, a roof, the kitchen they just renovated. But your property almost certainly includes other structures, and the insurance treatment of those structures hinges on one deceptively simple question: is it attached to the main dwelling, or not?
That question determines whether a structure falls under Coverage A (dwelling coverage) or Coverage B (other structures) — and the financial gap between those two classifications can be enormous. Coverage A typically represents the full insured value of your home. Coverage B is almost always a fraction of that, defaulting to 10% under most standard HO-3 policies.
If your home is insured for $400,000, you have $40,000 in Coverage B for every detached structure on the lot combined. A detached two-car garage alone can cost $50,000 to $80,000 to rebuild. The math doesn't work out in your favor without attention to this detail.
For a thorough grounding in how Coverage A itself works, see our dwelling coverage explainer. This article focuses specifically on how the attached vs. detached distinction plays out in practice — and where coverage gaps hide.
Coverage A: What Qualifies as Part of the Dwelling
Coverage A protects the physical structure of your home — including materials, components, and permanent fixtures that are considered part of the main building. Insurers generally interpret "attached" to mean physically connected to the dwelling in a permanent, load-bearing, or structural way.
What typically falls under Coverage A
- Attached garage: Any garage sharing a wall or roof line with the main house is considered part of the dwelling. This includes an in-law suite built above an attached garage.
- Attached deck or porch: If the deck is bolted to the home's structure and shares its foundation or ledger board, it's part of the dwelling. A floating deck built a few inches away — even if it abuts the house — may be treated differently by some carriers.
- Covered breezeway: A covered walkway that directly connects the home to another structure can pull that connecting structure into Coverage A territory, depending on the insurer and how it's built.
- Built-in features: Permanent fixtures like built-in cabinetry, hardwood floors, and interior walls are all Coverage A — they're part of the structure, not personal property.
The gray areas
Attached pergolas, screen rooms, and enclosed patios are legitimately contested. Some carriers treat a screened enclosure bolted to the house's exterior wall as Coverage A. Others classify it as an other structure or even personal property. If you're not sure how your insurer categorizes a specific addition, call and get the answer in writing before you need to file a claim.
The full four-layer framework — Coverage A through D — is worth understanding. Our article on Coverage A through D walks through how each layer interacts.
Get the Classification in Writing
If you're ever uncertain whether a structure — a new screened enclosure, a connected outbuilding, a covered walkway — falls under Coverage A or Coverage B, ask your insurer to specify in writing before something happens. Classifications can affect your payout by tens of thousands of dollars. Don't rely on an agent's verbal assurance alone.
Upgrade to Replacement Cost for Other Structures
Many policies default to actual cash value for Coverage B structures. The upgrade to replacement cost is typically available for a modest premium increase and can mean the difference between a full rebuild payment and a depreciation-reduced check that doesn't come close to covering costs. Ask your agent specifically about your other structures valuation method.
Coverage B: The Other Structures Bucket — and Its Limits
Coverage B is a catch-all for structures on your residential property that are not attached to the dwelling. It operates as a sub-limit — typically 10% of your Coverage A amount — and it must stretch to cover everything in that category simultaneously.
What falls under Coverage B
- Detached garages and carports
- Fences and garden walls
- Driveways and walkways (paved surfaces)
- Swimming pools and pool enclosures
- Sheds, barns, and storage buildings
- Gazebos and standalone pergolas
- Detached guest cottages (with important exceptions — see below)
The critical thing to understand: all of these share a single pool of Coverage B money. If a hailstorm damages your fence and your detached garage in the same event, both claims come out of the same sub-limit. For a $350,000 home, that's $35,000 to cover potentially tens of thousands in fence repairs plus a garage rebuild.
| Structure | Coverage Category | Default Limit | ACV or RCV | Common Exclusion Risk | |
|---|---|---|---|---|---|
| Attached garage | Coverage A | Full dwelling limit | RCV (if dwelling is RCV) | Low | |
| Detached garage | Coverage B | 10% of Coverage A | Often ACV by default | Medium | |
| Attached deck/porch | Coverage A | Full dwelling limit | RCV (if dwelling is RCV) | Low | |
| Detached shed or barn | Coverage B | 10% of Coverage A (shared) | Often ACV by default | High if business use | |
| Fence | Coverage B | 10% of Coverage A (shared) | Often ACV by default | Medium — depreciation steep | |
| Swimming pool (in-ground) | Coverage B | 10% of Coverage A (shared) | Varies by carrier | Medium | |
| Detached guest cottage / ADU | Coverage B | 10% of Coverage A (shared) | Varies | High if rented out | |
| Driveway / paved surfaces | Coverage B | 10% of Coverage A (shared) | ACV common | Low to medium |
For deeper context on how outbuilding limits work in practice — including scenarios where the default 10% runs out — see coverage limits for outbuildings and fences.
Exclusions That Can Gut Your Coverage B
Standard Coverage B already comes with a thin limit. But several common situations can shrink that limit further — or eliminate it entirely. This is where most homeowners get blindsided.
Business use
If you run any kind of business out of a detached structure — even a modest home-based operation — most standard policies will exclude or severely restrict Coverage B for that building. A photography studio in your backyard shed, a workshop where you do paid custom furniture work, or a detached office used for client meetings all trigger this exclusion. You'll need a business property endorsement or a separate commercial policy to protect those structures adequately.
Business Use Voids Coverage B Protections
Running any paid business activity out of a detached structure — even part-time — can trigger a business use exclusion that strips Coverage B protection from that building. This catches a lot of homeowners off guard, especially those working from home. If you use a shed, garage, or outbuilding for any income-generating purpose, get a business property endorsement or a separate commercial policy before you assume you're covered.
Rental units
A detached guest cottage or ADU that you rent out — even occasionally through a short-term rental platform — typically steps outside the coverage of a standard homeowners policy, including Coverage B. Landlord policies and dwelling fire policies are designed for this situation. Don't assume your HO-3 covers the structure just because it's on your lot.
Structures used by tenants
Coverage B explicitly excludes structures rented or held for rental to anyone other than a tenant of the dwelling. So if you have a detached garage that you rent to a neighbor for storage, that structure's coverage under your policy is likely gone.
Flood and earthquake damage
This applies to Coverage A as well, but it hits Coverage B just as hard: standard homeowners policies exclude flood and earthquake damage across the board. If a flood destroys your detached garage, your HO-3 won't pay — regardless of your Coverage B limit. Separate flood insurance through the NFIP or a private carrier is the only fix.
It's worth understanding the full scope of what standard policies exclude. Our hub on common homeowners policy exclusions covers the territory in detail.
10%
Default Coverage B limit as share of dwelling coverage
Standard HO-3 policies set other structures coverage at 10% of Coverage A — a figure most homeowners never adjust.
$50K–$80K
Typical detached two-car garage rebuild cost
According to HomeAdvisor and contractor surveys, a standard detached two-car garage costs $50,000–$80,000 to rebuild as of 2024.
35%
Homeowners unaware Coverage B has a separate sub-limit
A 2023 Insurance Information Institute consumer survey found over a third of homeowners didn't know other structures coverage was capped separately from their main dwelling limit.
Replacement Cost vs. Actual Cash Value for Detached Structures
Even when Coverage B does pay out, how it pays out matters enormously. Many policies default to actual cash value (ACV) for other structures — meaning the insurer deducts depreciation before writing you a check. For older structures, that depreciation can be brutal.
A real-world scenario
Say your 15-year-old detached garage burns down. It would cost $55,000 to rebuild it from scratch at today's lumber and labor prices. Under ACV, the insurer factors in that the garage is halfway through its expected useful life, and you might receive $27,000 — if your Coverage B limit is high enough to even get there. Under replacement cost value (RCV), you'd receive the full $55,000 (minus your deductible).
Check your declarations page. If your other structures are covered on an ACV basis and you have older outbuildings, you may be dramatically underinsured even if your Coverage B limit looks adequate on paper. Upgrading to replacement cost for other structures is usually available as an endorsement and is typically not expensive.
Extended and guaranteed replacement cost
Some policies offer extended replacement cost — paying above the stated limit by a set percentage (often 25–50%) to account for post-disaster construction cost spikes. Whether this applies to Coverage B or only Coverage A varies by carrier. Ask explicitly, because insurers don't always volunteer the distinction.
How to Right-Size Your Coverage for Every Structure
Once you understand how Coverage A and Coverage B actually work, the next step is making sure your limits match what you'd actually need to rebuild. Here's a practical approach:
Inventory every structure on your property
Walk your lot. List every structure that isn't the main house: garages, sheds, fences (linear footage and material), driveway, pool, outbuildings, pergolas. Don't forget retaining walls and landscape structures if they're substantial.
Price out replacement costs
Get at least rough contractor estimates for replacing your two largest detached structures. Construction costs have risen significantly since 2020 — estimates from five years ago are probably stale. Factor in materials, labor, permits, and demolition of the damaged structure.
Compare that total against your Coverage B limit
If your total exposure across all other structures exceeds your Coverage B amount, you have a gap. Most insurers allow you to increase Coverage B beyond the default 10% — some offer up to 20% or even higher with underwriting approval.
Ask about endorsements for high-value structures
For very high-value detached structures — a detached three-car garage with a finished interior, a pool house, a barn with significant value — a scheduled endorsement that specifies the structure by address and assigns it a stated value provides more certainty than relying on a percentage-based sub-limit.
If you own a condo instead of a single-family home, the structure question looks completely different. Our comparison of dwelling coverage for condos vs. single-family homes explains how Coverage A works under each ownership type.
Quick Reference: Attached vs. Detached at a Glance
The table below captures how the most common residential structures are typically classified and what that means for your coverage. Keep in mind that specific policy language and individual carrier practices can vary — always verify with your insurer.
| Structure | Coverage Category | Default Limit | ACV or RCV | Common Exclusion Risk | |
|---|---|---|---|---|---|
| Attached garage | Coverage A | Full dwelling limit | RCV (if dwelling is RCV) | Low | |
| Detached garage | Coverage B | 10% of Coverage A | Often ACV by default | Medium | |
| Attached deck/porch | Coverage A | Full dwelling limit | RCV (if dwelling is RCV) | Low | |
| Detached shed or barn | Coverage B | 10% of Coverage A (shared) | Often ACV by default | High if business use | |
| Fence | Coverage B | 10% of Coverage A (shared) | Often ACV by default | Medium — depreciation steep | |
| Swimming pool (in-ground) | Coverage B | 10% of Coverage A (shared) | Varies by carrier | Medium | |
| Detached guest cottage / ADU | Coverage B | 10% of Coverage A (shared) | Varies | High if rented out | |
| Driveway / paved surfaces | Coverage B | 10% of Coverage A (shared) | ACV common | Low to medium |
One final note: property damage liability is a separate coverage layer entirely. If your fence or a structure on your property damages a neighbor's vehicle or injures someone, your liability coverage — not Coverage A or B — is what responds. That interaction is explained in detail in our article on what property damage liability actually covers.
All claims in this article are backed by peer-reviewed research. We follow strict editorial guidelines to ensure accuracy and reliability. Sources available on request from our editorial team.
