The endorsement also provides instructions for calculating the percentage deductible. For blanket insurance, an amount equal to 2 percent (or whatever percentage is selected) of the value of the property, as reported on the most recent Statement or Report of Values, that has sustained loss or damage is deducted.

The endorsement provides an example of two buildings, each with a value of $500,000, that sustain losses. The first building sustains $40,000 in damage; the second sustains $20,000 in damage. Two percent of the first building's value of $500,000 ($10,000) is subtracted from the amount of the loss—the amount payable for the first building is $30,000. Another deductible equal to 2 percent of the second building's value of $500,000 is applied to its damage—$10,000 is subtracted from the $20,000 loss to yield an amount payable of $10,000. The most the insurer will pay is $40,000 after the application of the 2% wind deductible to those losses.

If the insured has an ISO endorsement, it is clear that a deductible applies to each building damaged and is calculated based on the value of the building, not on the amount of the damage. This point was also made in General Star Indemnity Company v. West Florida Village Inn, In., 874 So.2d 26 (Ct. App. Fla. 2004). Here, the court made the point that the deductible of 2 percent meant 2 percent of the policy limit. However, company-specific policies may not contain ISO's wording and may be unclear on how such deductibles apply.