Named Perils vs Open Perils (Special Form): How Property Form Choice Affects Coverage and Claims

Bottom line: For most commercial property placements, the ISO Special Form causes of loss form (CP 10 30) — open perils — is the correct default. It covers all direct physical loss except explicitly excluded causes, which means the insurer must prove an exclusion applies to deny a claim. Named perils forms (ISO CP 10 10 Basic, CP 10 20 Broad) flip that burden: the insured must prove the cause of loss is a listed peril to trigger coverage. Any loss from an unlisted cause — water intrusion with an ambiguous source, mechanical failure with disputed origin, a novel event — is simply uninsured. Named perils belongs on low-value storage risks, tenant equipment in surplus lines markets, and deliberate coverage-reduction decisions. It does not belong as the default choice when Special Form is available.

How Named Perils Coverage Works

A named perils property policy covers loss only from causes explicitly listed in the policy form. ISO publishes two named perils causes of loss forms under the Commercial Property program:

ISO CP 10 10 — Basic Form. Covers eleven named perils: fire, lightning, explosion, windstorm or hail, smoke, aircraft, vehicles, riot or civil commotion, vandalism, sprinkler leakage, and volcanic action. This is the narrowest commercially available causes of loss form. A roof that collapses under accumulated snow weight — not a listed peril — is uncovered. A burst pipe due to freezing — not listed — is uncovered. Water damage from a malfunctioning HVAC system — not listed — is uncovered.

ISO CP 10 20 — Broad Form. Adds six perils to the Basic Form list: falling objects, weight of snow, ice, or sleet, water damage from accidental discharge or leakage from plumbing, heating, cooling, or fire protection systems, collapse as defined in the Broad Form, and glass breakage. The Broad Form is more commonly placed than Basic Form for occupied commercial buildings but still leaves substantial gaps compared to the Special Form.

Under both named perils forms, the insured carries the burden of demonstrating that the cause of loss is a covered peril. When the cause is ambiguous — a slow leak that caused mold, a roof failure where both wind and deferred maintenance played a role — named perils policies generate coverage disputes that open perils policies typically resolve in the insured's favor.

How Open Perils (Special Form) Coverage Works

The ISO CP 10 30 Special Form is an open perils causes of loss form: it covers direct physical loss to covered property unless the loss is caused by a specifically excluded peril. The insuring agreement in CP 10 30 reads, in substance, that the insurer will pay for risk of direct physical loss to covered property — and then the exclusions define the limits of that promise.

This inversion is the critical structural difference. Under the Special Form, the insurer bears the burden of demonstrating that a specific exclusion applies to deny a claim. When the cause of loss is ambiguous, unknown, or novel, the default is coverage — not exclusion.

The Special Form is the industry standard for most commercial property placements. ISO's Building and Personal Property Coverage Form (CP 00 10) is almost universally paired with the Special Form for occupied commercial buildings and business personal property. The Business Owners Policy (ISO BP 00 03) applies Special Form coverage to both building and business personal property by default — open perils is built into the BOP structure.

The Burden of Proof Difference — Why It Matters in Claims

The practical consequence of named perils versus open perils is most visible at claim time.

Named perils claim scenario: A client's warehouse sustains water damage after an unusual weather event. The cause is unclear — possibly wind-driven rain entering through a roof seam, possibly ground-level flooding from adjacent soil saturation. Under a Basic Form or Broad Form policy, the insured must demonstrate the loss resulted from a listed peril. If the adjuster concludes the water entered from the ground rather than wind-driven rain through an opening, the claim is denied: flood is not a listed peril, and ground-level intrusion is not the same as windstorm. The insured either pays out of pocket or disputes through appraisal or litigation.

Special Form claim scenario: Same warehouse, same ambiguous water loss. Under the Special Form, the question is whether the insurer can invoke a specific exclusion. The flood exclusion in CP 10 30 — ISO CP 10 30, Section B.1.g — excludes flood defined as surface water, waves, tides, tidal waves, overflow of a body of water, or spray from any of these. If the adjuster cannot establish that the water intrusion falls within this specific definition, coverage applies. Ambiguity defaults to the insured.

This difference produces measurably different claim outcomes for identical losses. Named perils policies generate significantly more coverage disputes and declinations on ambiguous causation, which erodes client trust and creates E&O exposure for the broker who placed coverage without explaining the limitation.

What the Special Form Excludes

Open perils does not mean all perils. CP 10 30 contains a defined list of excluded causes of loss. Understanding these exclusions is essential — they represent the actual coverage gaps in a Special Form placement that require separate endorsement or standalone policies to address:

Earth movement (CP 10 30, Section B.1.b). Earthquake, landslide, subsidence, earth sinking or shifting, volcanic eruption (other than volcanic action listed in the Basic Form), and mine subsidence. Earthquake coverage must be added by endorsement (ISO CP 10 40) or surplus lines policy.

Flood (CP 10 30, Section B.1.g). Surface water, waves, tidal overflow, storm surge, and spray from any of these sources. Commercial flood coverage is available through the National Flood Insurance Program (NFIP) under its Commercial Property policy or through private surplus lines flood carriers — it is not available by endorsement to a standard property form.

Ordinance or law (CP 10 30, Section B.1.a). Loss caused by enforcement of building codes or ordinances requiring demolition, reconstruction to current code standards, or suspension of use. When a partial loss to an older building triggers a municipality's requirement to bring the entire structure to current code, the ordinance or law exclusion removes the upgrade cost from the base policy. The ISO Ordinance or Law endorsement (CP 04 05) closes this gap and should be offered on any building constructed prior to the current code cycle.

Utility service interruption (CP 10 30, Section B.1.d). Loss caused by interruption of power, water, gas, or other utility service supplied from outside the described premises — even if the interruption itself is caused by a covered peril. The Utility Services — Time Element endorsement (CP 15 45) and Utility Services — Direct Damage endorsement (CP 15 45) close this gap for clients with significant utility dependency.

Mechanical or electrical breakdown. Deterioration, wear and tear, rust, corrosion, decay, and latent defect are excluded in CP 10 30. Equipment breakdown (formerly boiler and machinery) coverage, available as a standalone policy or ISO equipment breakdown endorsement, addresses sudden and accidental mechanical or electrical failure.

Fungi, wet rot, dry rot, and bacteria. Added to the ISO standard forms in 2002, this exclusion applies to loss caused by or resulting from fungal growth (mold), wet or dry rot, or bacterial contamination — subject to limited coverage for resulting loss if the fungi or rot results from a specified cause of loss (fire, lightning, explosion, windstorm, or hail, aircraft, vehicles, riot). Mold remediation claims frequently involve this exclusion.

Pollutants. Discharge, dispersal, seepage, migration, or escape of pollutants — with a narrow exception for loss caused by fire, explosion, lightning, or aircraft. Contractors, dry cleaners, auto service businesses, and any client handling regulated substances face significant exposure here without a pollution liability policy. PFAS (per- and polyfluoroalkyl substances) are now subject to specific CGL exclusion endorsements beyond this standard pollutants language — see PFAS Exclusions in Commercial Insurance for how carriers are applying these endorsements and what specialty markets remain available.

Side-by-Side Comparison

When Named Perils Makes Sense

Named perils coverage is appropriate in specific, deliberate circumstances — not as a default:

Low-value or unoccupied storage properties. A warehouse storing non-perishable goods where the primary exposure is fire and windstorm, and the client understands and accepts the limitation, is a reasonable candidate for Basic Form coverage at a lower premium.

Surplus lines placements with limited carrier appetite. Some hard-to-insure properties — high-hazard occupancies, properties with severe loss history, or specialty risks — may only be available in the surplus lines market, where named perils forms are sometimes the only option the underwriter will write. This is a market-driven constraint, not a coverage preference.

Client-directed coverage reduction with documented disclosure. Occasionally a sophisticated client with multiple locations and a captive or self-insured retention structure makes a deliberate decision to purchase Basic or Broad Form on secondary locations to reduce premium. This decision must be documented in writing: the broker should provide a written comparison of the forms, obtain the client's signed acknowledgment of the limitation, and retain both documents in the file. Without this documentation, an uninsured loss from an unlisted peril becomes E&O exposure.

Tenant improvements for short-term leases. A tenant with a 12-month lease who installed minimal improvements in a space may rationally accept a named perils form at lower premium for the short hold period. Once a client has material improvements and betterments or business personal property of significant value, Special Form is the appropriate default.

When Special Form Is the Right Choice

Special Form applies to the overwhelming majority of commercial property placements:

Any occupied commercial building. A business that depends on its building for operations — a restaurant, a medical office, a manufacturer, a retail shop — faces too many possible causes of loss to accept the exposure created by a named perils form. Ambiguous water events, unknown collapse triggers, and emerging loss causes (theft, employee dishonesty to property) all benefit from the open perils structure.

Business personal property with significant value. Inventory, equipment, and tenant improvements are the economic core of most commercial clients' operations. Losses from causes that fall outside named perils lists — a mystery power surge, a slow leak of ambiguous origin, a break-in where it is unclear whether entry was forced or incidental — can be substantial and may be denied under named perils. Special Form closes these gaps.

Any property loss that triggers business income. When a covered property loss suspends operations and activates business income coverage, the scope of the property form directly determines which losses trigger the BI benefit. A loss excluded under a named perils property form does not trigger BI coverage either — because BI coverage under ISO CP 00 30 applies only when the loss results from a covered cause. A client with a 6-month BI exposure who sustains a property loss from an unlisted cause gets nothing from either coverage line.

Any account where a coverage dispute would produce a client relationship failure. Named perils policies generate coverage arguments at the worst possible moment — immediately after a loss. Unless the client explicitly understands and accepts the form limitation, discovering the gap in the context of a denied claim destroys the relationship and triggers regulatory complaints.

Endorsements That Close the Special Form's Key Gaps

The Special Form is the starting point, not the complete solution. After placing Special Form coverage, evaluate each of the following endorsements:

• Ordinance or Law (CP 04 05): Required for any pre-code building. Covers demolition, increased cost of construction, and loss to the undamaged portion of the building when code enforcement requires it. Offer on every pre-2000 commercial building.
• Earthquake (CP 10 40): Required in seismic zones (California, Pacific Northwest, New Madrid zone) and available in most admitted markets as an endorsement or standalone policy.
• Flood: NFIP Commercial policy or private surplus lines flood carrier. Required for any property in a FEMA Special Flood Hazard Area (Zone A or V) and worth evaluating for properties in Zone X with ground-level exposure.
• Equipment Breakdown: Covers sudden and accidental mechanical or electrical failure — the mechanical breakdown exclusion in CP 10 30 creates a significant gap for manufacturers, restaurants, medical offices, and any client with significant equipment values.
• Utility Services (CP 15 45): Extends coverage to property damage and business income loss caused by utility interruption from outside the premises when the interruption results from a covered cause.

The causes of loss form selection is a required field in a commercial property underwriting submission. See the commercial property underwriting guide for the complete COPE data, replacement cost, and ACORD 140 submission process.

FAQ

What is the difference between named perils and all-risk coverage?

"All-risk" is a colloquial term for open perils or Special Form coverage. There is no ISO form called "all-risk" — the industry term is open perils or special form. All-risk coverage means the policy covers all direct physical loss except specifically excluded causes. Named perils means the policy covers only the causes explicitly listed.

Does a Business Owners Policy (BOP) use named perils or open perils?

The ISO Business Owners Program (form BP 00 03) applies Special Form (open perils) coverage to both buildings and business personal property by default. This is one of the reasons BOPs are generally well-suited to small commercial risks — the open perils structure avoids the coverage gaps that Basic and Broad Form named perils forms create.

Who has the burden of proof under a named perils vs. open perils policy?

Under a named perils policy, the insured must demonstrate that the cause of loss is a listed peril to trigger coverage. Under an open perils (Special Form) policy, the insurer must demonstrate that a specific exclusion applies to deny coverage. This difference is critical at claim time: ambiguous or unknown causes default to denial under named perils and to coverage under Special Form.

Is theft covered under named perils or open perils?

Theft is not a listed peril in either the Basic Form (CP 10 10) or the Broad Form (CP 10 20). It is covered under the Special Form (CP 10 30), subject to the theft limitations in the form (theft of construction materials, furs, jewelry, and certain property types have sublimits or exclusions). For named perils policies, separate crime coverage must be purchased to insure theft.

Can I place open perils coverage on a property with a poor loss history?

Some carriers will decline to offer Special Form coverage on properties with adverse loss histories, vacant buildings, or high-hazard occupancies — particularly in a hard market. In these situations, the surplus lines market is usually the placement path. Surplus lines carriers may offer Special Form coverage at higher premiums, or may only offer named perils. This is a market constraint, not a coverage preference, and should be disclosed to the client when explaining why the placement came back on a named perils form.

What does "direct physical loss" mean in the Special Form?

"Direct physical loss" requires a physical alteration to the property — not purely economic loss or loss of use without physical damage. Courts have interpreted this requirement in various ways, particularly after COVID-19 business income disputes. Under the Special Form, property must sustain tangible, identifiable physical change to trigger coverage. Contamination that requires cleaning, loss of utility that does not alter the structure, and purely aesthetic changes may fall outside "direct physical loss" depending on jurisdiction and the specific facts.

How does the property form choice affect business income coverage?

Business income coverage under ISO CP 00 30 is triggered by "direct physical loss or damage to property at the described premises" caused by a covered cause of loss. The property form and the business income form use the same covered causes of loss definition. A loss that is denied under a named perils property form — because the cause is not a listed peril — also fails to trigger business income. A client with a named perils property form has effectively accepted the same gap in their BI coverage. This linkage is one of the most important reasons to place Special Form property coverage for any client with significant BI exposure.

When should I recommend named perils to a client?

Named perils coverage is appropriate when: the client has a low-value property with minimal operations (vacant storage, secondary location with minimal contents), the client explicitly understands and accepts the coverage limitation in writing, or the market will only write the risk on a named perils basis. Named perils should never be the default recommendation — it is a deliberate coverage reduction that must be explained and documented.

Arvori helps insurance brokers manage client accounts, track coverage gaps, and coordinate with CPA partners — from one platform. See how Arvori works for commercial lines brokers.