When you buy a co-op apartment, (a housing unit of which you hold a share of the corporation that owns and manages the unit) the building will already have an insurance policy that protects itself and shareholders for claims resulting from lead paint exposure, sewer backups, earthquake damage and other events that might affect the entire building. Cooperative insurance covers claims that affect individual shareholders and the personal belongings inside their units. It is advisable to find out what the building association's insurance policy covers prior to signing up for a co-op insurance policy.