Hail damage or wear? Telling shingle problems apart

Two roofs can have the same number of marks and need completely different responses. Hail damage is a storm event, and home insurance policies generally deal with sudden damage from storms differently from wear and tear. Your policy wording decides what's covered. Blisters, weathering and nail problems come from age, the product or the installation, and the fix may be a repair, a warranty question or a replacement on your own schedule.

Getting the cause right also avoids two expensive mistakes: filing a claim on a roof that's simply old, and living with real hail damage because it was written off as wear.

The Insurance Institute for Business & Home Safety (IBHS) lists the signs of hail on an asphalt shingle roof:

Blisters form when gas or moisture trapped in a shingle swells and eventually pops, leaving a small crater. The InterNACHI inspection narrative library describes blisters as small, steep-sided craters, a quarter inch (6 mm) or less across, with no granules visible in the crater and a flat bottom of fairly uniform depth. It lists causes such as excessive heat, moisture and incompatible adhesives. IKO's application instructions also warn that too much roofing cement can make shingles blister.

Hail hits look different up close. According to the same InterNACHI reference, a hail strike usually still has granules in the damaged area, and the excavation has a sloped bottom shaped by the hailstone rather than a flat one.

Granules protect the asphalt from sunlight, and every roof loses some over its life. InterNACHI explains that the bond between granules and asphalt deteriorates over time, and the loosened granules are carried away by runoff. IBHS notes that granule loss along the edges of shingles is normal weathering, and that uniform wear or discoloration isn't hail. Heavy rain can knock granules off too.

Age also changes the shingle itself. Travelers notes that exposure to weather and sunlight makes shingles brittle, and lists blistering, cracking, granule loss, flaking and algae as normal wear that can be mistaken for hail.

Not every mark came from the sky. IBHS lists marks caused by installation, tools and people as things that aren't hail damage. InterNACHI notes that granule loss along a natural path of travel on the roof, like the route from a ladder to a satellite dish or a chimney, is usually scuffing from foot traffic.

The giveaway is the pattern: marks in a line, around equipment, or right where a ladder would land, rather than scattered across every slope.

A nail pop is a nail that has backed out and lifts the shingle above it. InterNACHI describes how nailing goes wrong:

Wind leaves its own signs: creased shingles that were lifted and folded back, broken seals, and missing tabs, usually starting at corners, rakes and ridges where uplift is strongest. Wind damage to shingles covers it in detail.

Here's how the common problems compare. It's a guide to reading a report, not a substitute for an inspection.

Stay off the roof. Look from the ground with binoculars, check the eavestroughs, downspouts and air conditioner for dents, and take dated photos. Note the date of any storm. Then have someone qualified inspect it up close, with fall protection, and ask them to explain in the report how they decided the cause.