When a roof has been exposed to a hailstorm severe enough to cause granules to be dislodged from the surface of the shingles (in spots large enough which expose the asphalt), the roof has been compromised. The colored granules which are placed on the surface of the shingle to serve two purposes:
Heavy hail damage is obvious because of the indentations in the shingle. When the surface damage of the shingle is not visible, look for indentations on vents, ridge vents, siding, or any other softer metal objects that may show impact. The effects on the shingle may not be apparent for about a year. At this time, circular areas of granules will fall off the shingle. This is often called spalling. What has occurred is that the impact of the hailstone has broken or weakened the bond between the granules and the asphalt. After a year or so of weathering, the granules fall off the shingle in the circular area of impact. With granules missing, the sunlight (UV) quickly attacks the asphalt and the maximum performance of the shingle has been compromised. The Manufacturers Warranty on Roofing Shingles is void when shingles are damaged due to the evidence of hailstorms under all conditions stated above.
Composite shingles are designed to protect your roof from water by using a tar/asphalt layer covered by gravel and granules that protect the tar from the UV rays of the sun. This means that hail can cause future damage to a roof by dislodging the granules on the surface of shingles. To document damage from hailstorms that may not be immediately visible, track changes in shingle appearance and excess granules in gutters or under eaves for weeks and months after a hailstorm. We recommend calling your insurance company immediately after the storm, and note that there is no apparent damage after the storm, but that you will document any future loss of granules or appearance of bare shingles in the next few months. Make notes on any changes in your roof after each rainstorm, with the date and observed change (e.g. rain on May 12, 2 weeks after hail storm, significant granules found in gutters). Photographs can also help support your case, as long as the date is included on the picture.
Even a moderate hailstorm can cause damage to a roof. The tricky part of assessing this damage is that it may not be obvious immediately after the storm, and different types of roofing materials will experience different kinds of damage.
Hail damage can dislodge the protective mineral granules of an asphalt shingle, producing areas of exposed asphalt shingle substrate. If inspecting an asphalt shingle (or mineral-granule-covered roof roofing) roof shortly after a hailstorm the exposed shingle substrate should be expected to show freshly-exposed asphalt coated or asphalt impregnated shingle base material. If the same area is examined much later the exposed shingle areas of granule loss may have weathered or even cracked and this distinction (hail versus wear or other sources of granule loss) will be more difficult to distinguish.
