The stated percentage is usually 80%, 90%, or 100% of the property value for a co-insurance clause. For example, a $1 million building with 80% co-insurance must be insured for no less than $800,000. If the policy holder chooses to insure the building for less than $800,000, they agree to retain part of the risk with the insurance company. The policy holder becomes the co-insurer absorbs the co-insurance penalty when there’s a claim.