Insurance companies sometimes deny claims because the damage was caused by a pre-existing defect in the property.  The roof let water in because it was poorly constructed for example.

The insurance policy will often exclude “wear and tear” and damage caused by the failure to maintain the home. For example, a storm may blow tiles off your roof. We may refuse to pay the claim if your house was old and the tiles needed replacement anyway because of their age. Insurance policies are not a substitute for failing to maintain your home.

To avoid a claim rejection because of wear and tear in the example above you need to try to get evidence to show that the damage was caused by a storm or other event covered by the policy, evidence of regular maintenance work and inspections and the state of repair of the home generally.