Property Insurance Exclusions: What Standard Policies Don’t Cover and How to Fill the Gaps

The ISO HO-3 Special Form is an open-perils policy on the dwelling — it covers all direct physical loss unless specifically excluded. The exclusion list is therefore the most important section of the policy for risk management purposes: it defines the boundaries of coverage and identifies where separate policies, endorsements, or self-insurance programs are required to complete the risk transfer. The exclusions most commonly encountered in property claims — and most likely to produce unexpected coverage gaps at claim time — are flood, earth movement, ordinance or law, sewer backup, service line, and mold.

For a full understanding of the coverage structure that these exclusions carve out from, see Property Insurance Policy Structure: Coverage A, B, C, D and How Each Applies. For the valuation methods that apply when coverage does exist, see Property Insurance Claims Valuation: ACV, RCV, and Agreed Value Methods.

Flood Exclusion

The flood exclusion is the single largest source of uninsured property loss in the United States. ISO HO-3 and standard commercial property policies exclude all damage from surface water, overflow of bodies of water, waves, tidal water, storm surge, flooding, and water that backs up from any of these sources — regardless of the cause of the flooding. The exclusion applies whether the flood results from a named hurricane, a 500-year rainfall event, spring snowmelt, or a dam failure upstream.

Definition — Flood (ISO HO-3 Exclusion): Flood, surface water, waves, tidal water, overflow of a body of water, or spray from any of these, whether or not driven by wind; water that backs up through sewers or drains from flood; and water below the surface of the ground including water that exerts pressure on a foundation. Excluded under standard ISO HO-3, ISO HO-5, and ISO CP commercial property forms.

The National Flood Insurance Program (NFIP), administered by FEMA under the National Flood Insurance Act of 1968, is the primary mechanism for residential flood insurance in the United States. NFIP provides coverage in participating communities (over 22,000 communities as of 2025) for residential structures up to $250,000 building coverage and $100,000 contents coverage. NFIP premiums are set by FEMA’s Risk Rating 2.0 methodology, implemented in 2021, which bases premiums on individual property flood risk including elevation, proximity to flood sources, and structure characteristics — replacing the legacy FIRM (Flood Insurance Rate Map) zone-based pricing.

NFIP limitations create coverage gaps for higher-value properties and commercial risks: the $250,000 residential building limit is insufficient for any home with a replacement cost above that threshold; NFIP provides no business interruption coverage; NFIP contents coverage excludes items in basements; and NFIP does not cover additional living expenses. Private flood insurance from admitted and surplus lines carriers fills these gaps — higher limits (up to $15M+ on commercial), broader coverage, broader definition of flood, and competitive pricing in lower-risk zones.

Earth Movement Exclusion

The earth movement exclusion in ISO HO-3 goes beyond earthquakes. The full exclusion encompasses: earthquake, landslide, mudflow or mudslide, subsidence, sinkholes, erosion, and any movement of earth including rising, sinking, or shifting — whether caused by natural processes or human activity. Subsidence from groundwater depletion (common in arid western states), mining subsidence, construction vibration-induced soil movement, and karst sinkhole formation are all excluded under the standard earth movement exclusion.

Earthquake coverage: available as a standalone policy or endorsement in all states, with pricing determined by USGS seismic hazard zone classification. California, the Pacific Northwest, Alaska, the New Madrid Seismic Zone (Missouri, Tennessee, Arkansas, Illinois, Kentucky), and the Intermountain West carry the highest seismic hazard ratings. California residential earthquake insurance is primarily provided through the California Earthquake Authority (CEA), a publicly managed entity created in 1996 after the 1994 Northridge earthquake destabilized the private residential earthquake market. CEA policies typically carry a 10–25% deductible of the policy limit — a $500,000 policy with a 15% deductible requires the policyholder to pay $75,000 before coverage applies. Earthquake insurance is significantly underutilized relative to actual seismic risk in California and the Pacific Northwest.

Sinkhole coverage: Florida Statute §627.706 requires all admitted carriers selling residential property insurance in Florida to offer sinkhole coverage. Carriers must provide catastrophic ground cover collapse coverage (full structural collapse) as a base policy element; sinkhole loss coverage (damage from actual sinkhole activity without full collapse) is available as an endorsement. Tennessee, Texas, Missouri, and Pennsylvania have significant sinkhole activity but no mandatory coverage requirements.

Ordinance or Law Exclusion

The ordinance or law exclusion removes coverage for the increased cost of construction required by current building codes when rebuilding or repairing after a covered loss. The exclusion applies in three distinct scenarios: demolition of the undamaged portion of the structure required by code (a “50% rule” that requires full demolition if damage exceeds 50% of value); increased cost of rebuilding the damaged portion to current code; and loss in value to the undamaged portion resulting from enforcement of ordinances or laws.

Without the ordinance or law endorsement, a policyholder rebuilding a 1960s home after a covered fire receives only the cost to replicate the original construction specifications. The building department, however, requires current code compliance: updated electrical panels, AFCI breaker protection on all branch circuits (NEC 210.12(A)), GFCI protection at all required locations, current energy code insulation R-values (IECC 2021), and potentially ADA provisions for commercial structures. These code-mandated costs are not covered without the endorsement.

The ordinance or law endorsement is typically available in limits of 10–50% of the Coverage A limit. For properties with significant code gap exposure — homes built before 1970, commercial structures in jurisdictions with active code enforcement, historic buildings in preservation districts — the maximum available limit should be purchased. FEMA estimates that code upgrades represent 15–25% of residential reconstruction costs after major loss events in older housing stock markets.

Sewer Backup and Sump Pump Overflow Exclusion

ISO HO-3 excludes water damage that backs up through sewers or drains and water that overflows from a sump pump, sump pump well, or similar system. The exclusion applies regardless of cause — a municipal sewer system overwhelmed by heavy rain, root infiltration of the building’s lateral sewer line, a sump pump that fails during a high-water-table event, or a drain valve that malfunctions all produce the same coverage result: excluded.

This exclusion is particularly consequential for properties with finished basements and homes in areas with combined sewer systems (where storm water and sanitary sewer share infrastructure). A sewer backup event in a finished basement — wet bar, home theater, guest bedroom, bathroom — can cause $30,000–$80,000 in damage. Sewer backup coverage endorsements are available from most carriers at $50–$150 annually for limits of $5,000–$25,000. These limits are frequently inadequate for finished basements; higher limits should be sought, and the endorsement should be purchased regardless of perceived backup risk.

Service Line Coverage Gap

Standard homeowner’s policies do not cover damage to underground service lines — the water supply line from the street meter to the foundation, the sewer lateral from the foundation to the municipal connection, the underground gas line, and underground electrical conduit. The property owner is typically responsible for the service lines from the property line to the structure (and in some municipalities, from the street tap). Failure of these lines is common — root infiltration, soil movement, material failure in aging clay or cast-iron pipe, and corrosion — and repair costs range from $3,000 to $15,000+ depending on line type, depth, and access conditions.

Service line coverage endorsements are available from most homeowner’s carriers for $25–$60 annually, covering underground service line repair or replacement up to $10,000–$25,000 per event. This is one of the highest-value endorsements available on a cost-per-dollar-of-coverage basis and is among the most frequently recommended additions to a standard HO-3 policy.

Mold Limitation and Exclusion

Following significant mold claim losses in the late 1990s (Texas was particularly affected, with mold claims reaching $4.2 billion in 2001–2002), most carriers added mold exclusions or sublimits to residential policies by 2003. The standard mold limitation excludes mold that results from a long-term or repetitive moisture condition — a chronic roof leak, persistent condensation, inadequate ventilation — but typically preserves coverage for mold that results directly from a sudden and accidental covered peril, such as a pipe burst that creates conditions for mold growth.

The covered-peril mold coverage is frequently disputed in claims: carriers argue the mold resulted from pre-existing moisture conditions; policyholders argue it resulted from the covered water event. Resolution turns on the timeline — mold visible within 48–72 hours of a covered water event is generally accepted as loss-related; mold discovered weeks later requires documentation establishing causation. ANSI/IICRC S520 Standard for Professional Mold Remediation provides the technical framework for causation analysis in contested mold claims.

Intentional Loss and Fraud Exclusions

All property policies exclude intentional loss — damage intentionally caused by the insured. Less commonly understood is the innocent co-insured doctrine: when one insured intentionally causes a loss, most carriers take the position that the exclusion voids coverage for all named insureds, including the innocent spouse or co-owner who had no knowledge of or participation in the act. A minority of states have enacted innocent co-insured statutes providing coverage to the innocent party; in the majority of states, the exclusion is enforced against all named insureds jointly, potentially leaving the innocent co-insured without coverage for the loss caused by their co-insured’s intentional act.

Frequently Asked Questions