The windstorm or hail clause found in the covered causes of loss section—basic and broad forms of the simplified language commercial property program of Insurance Services Office (CP 10 10 10 12 and CP 10 20 10 12, respectively) follows.

 Covered causes of loss means "windstorm or hail, but not including:

1. frost or cold weather;
2. ice (other than hail), snow or sleet, whether driven by wind or not; or
3. loss or damage to the interior of any building or structure, or the property inside the building or structure, caused by rain, snow, sand or dust, whether driven by wind or not, unless the building or structure first sustains wind or hail damage to its roof or walls through which the rain, snow, sand or dust enters.

 A common type of claim reached by this exclusion is water damage to walls, ceilings, or personal property that occurs during a windstorm but for which there is no apparent source. Sometimes this type of damage results from seepage around window casings or eaves that are of adequate soundness for ordinary weather but not for hurricanes or similarly violent happenings.

There is no such exclusion on either the ISO special perils form CP 10 30 10 12 or the HO-3. However, CP 10 30 does include a limitation of coverage that is similar but not as restrictive, and this type of coverage for personal property on a HO-3 does produce a similar effect. The limitation of coverage on CP 10 30 states that there is no coverage for loss or damage to property to:

c.  The interior of any building or structure, or to personal property in the building or structure, caused by or resulting from rain, snow, sleet, ice, sand or dust, whether driven by wind or not, unless: