Multiple disasters
If a home is damaged by two or more perils, and one of the perils in question is not covered, then the whole claim can be denied. This is called “anti-concurrent causation clauses.” Such claim loopholes saw public scrutiny in the wake of Hurricane Katrina. Basically, the insurer doesn’t want to be liable for catastrophic damages created in the wake of multiple natural disasters.
For example, consider a home that sustains structural damages from hurricane-force winds. Then, a flood destroys items in the home and creates a mold problem. If the homeowner doesn’t have any flood insurance the claim can be denied.