peril and covered cause of loss

When something bad happens to your property, there is always a reason it happened: a fire, a windstorm, a burst pipe, a thief. That reason — the thing that actually does the damage — is the peril, also called the cause of loss. Insurance does not simply pay for 'damage'; it pays for damage caused by a peril the policy agreed to cover. So a roof flattened by a tornado may be paid, while the same roof sagging from years of neglect is not, because wear-and-tear is not an insured peril.

Policies split into two styles of saying which perils count. A 'named perils' policy lists exactly what is covered — fire, lightning, hail, theft — and anything not on the list is excluded; you must show your loss came from a listed peril. An 'all-risk' (or 'open perils') policy flips this: everything sudden and accidental is covered EXCEPT what the exclusions list (like flood, earthquake, war, or gradual deterioration). All-risk is broader but is not truly 'all' risk — the exclusions still carve out the big systemic perils that need their own coverage. The phrase 'covered cause of loss' is just the formal way of saying 'a peril this policy actually pays for'.

Peril definitions matter to actuaries because each peril has its own frequency and severity behaviour, and some perils are catastrophic (one windstorm hits a whole region at once) while others are independent (one kitchen fire affects one house). Pricing and reserving often break a line down by peril; catastrophe models are built peril by peril (hurricane, earthquake, wildfire). A subtle, important point: causation can be disputed — if a hurricane's wind is covered but its flood is excluded, deciding whether wind or water destroyed a house can be a multi-billion-dollar question.