Definition:Causes of loss form
📄 Causes of loss form is a standardized document, most commonly published by the Insurance Services Office (ISO), that specifies which perils are covered — and which are excluded — under a commercial property insurance policy. Rather than embedding peril definitions directly in the policy declarations, insurers attach one of several causes of loss forms, each offering a different breadth of coverage. The three principal ISO versions are the Basic Form, the Broad Form, and the Special Form, each progressively expanding the range of covered causes of loss.
📐 The Basic Form covers a limited list of specifically named perils such as fire, lightning, explosion, windstorm, hail, smoke, vandalism, and certain types of water damage. The Broad Form adds perils like falling objects, weight of snow or ice, and water damage from plumbing systems. The Special Form takes a fundamentally different approach: instead of listing what is covered, it covers all causes of loss unless specifically excluded — effectively creating an all-risk structure. Underwriters select the appropriate form based on the risk profile of the insured property, the premium the policyholder is willing to pay, and the carrier's own underwriting guidelines. Endorsements can further modify any form, adding back excluded perils or imposing sublimits and additional deductibles.
🧭 For anyone working in commercial property insurance — from brokers advising clients to adjusters evaluating losses — fluency in these forms is indispensable. The form attached to a policy often determines the outcome of a coverage dispute more decisively than any other document, because it controls the causation analysis: if the peril is not within the form's grant, the claim does not proceed. Courts have built extensive case law around the interpretation of causes of loss form language, especially around exclusions for flood, earth movement, and ordinance or law. Standardization through ISO forms also creates consistency across the market, allowing reinsurers and rating agencies to evaluate portfolios with a shared understanding of what each policy actually covers.
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