I'd check what the policy's stance is on 'consequential damage'. Also consider:
- Whether the leak occurred during the period of coverage.
- Whether the leak itself was an insurable event.
- Whether the leak, if insurable, was reported to the insurer within the required time (whether this is calculated from when it happened, or when it was discovered - could be either).
- How long it took to do the damage.
- Whether the damage was discoverable.
- What steps should have been taken that may have led to the leak being discovered.
- What steps should have been taken to rectify any discoverable damage, but which were not taken.
Insurance companies are not your friend, and they will split hairs on coverage issues.