What is hail damage on a roof?

What it is

Hail forms when a thunderstorm's updraft carries raindrops high enough to freeze and keeps them aloft while layers of ice accrete; the Storm Prediction Center records the National Weather Service's definition of a severe thunderstorm as one producing hail of one inch in diameter or larger, damaging wind or a tornado, and larger stones fall faster and hit harder. A hailstone striking an asphalt shingle at that speed crushes the granule surface into the mat beneath: the mark is a soft, dark, roughly circular bruise where the granules are gone and the asphalt shows, sometimes with a fracture of the mat you can feel with a thumb. On metal roofing and flashing it leaves round dents; on slate, tile, wood shakes and skylights it cracks or splits.

Bruises are the damage that matters, because the exposed asphalt then weathers and the mat cracks. Scattered granule loss in gutters after a storm is not, by itself, hail damage — granules shed with age — which is why an inspection looks for the pattern: random hits of similar size across a slope, heaviest on the side the storm came from, matching dents on soft metals such as vents and gutters.

What it costs and who does it

Hail repair ranges from replacing a few slopes to a full re-roof, priced by the square as any replacement is, with the insurer's adjuster and the contractor's estimate usually reconciled to the same scope; dented vents, flashings and gutters are line items. A roofing contractor does the work, and many in hail regions employ staff who handle the claim paperwork. The directory's storm-damage repair guide covers the sequence from inspection to claim, and its storm damage repair cost guide explains how those estimates are built.