How Can You Tell Old Hail Damage From New Hail Damage?

Colour. Freshly exposed asphalt is black, and asphalt that has been exposed for several months oxidises to a grey surface film. That single test, published by Haag Engineering and used by forensic inspectors everywhere, is the clearest way to separate damage from a recent storm from damage that has been there for years, and it works on a photograph without anyone climbing a ladder. Arrowhead Roofing has been reading Tulsa roofs since 1987, and this is the check that most often settles the argument.

Note: this is a general explanation of how hail damage is dated. It is not a statement about any particular policy. Arrowhead Roofing is not a licensed public adjuster and we do not negotiate insurance claims. What your policy covers is determined by your policy and your carrier.

Four indicators, and they can be read together rather than one at a time.

The Short Answer

Asphalt weathers by photo-oxidation. Sunlight acts on the exposed bitumen, and it changes colour in a predictable direction: black when it is first uncovered, progressively grey as a surface film forms.

That is not only a field observation. The assessment protocol carried by the National Roofing Contractors Association describes weathered exposure in the same terms, as bitumen showing a weathered grey colour.

The description in Haag’s own technical literature is worth having in the words they used: recently exposed asphalt appears black or unweathered, whereas asphalt exposed for several months oxidises, forming a surface film that is grey in colour.

Andy Anderson at Arrowhead puts the same thing the way a homeowner can use it:

The old asphalt where the granules have been knocked loose turns chalky and gray and it weathers out over time. Where the new hail, they’re black. The asphalt is exposed. It’s just been recently exposed, so it’s black.

How Precise Is This, Honestly

Not very, and that matters more than a false precision would.

The published figures are “several months” for black to grey, and years for a fracture edge to weather from sharp to rounded. That is the extent of what the engineering literature commits to.

If a page tells you hail damage turns grey in thirty days, or in six months, that number is invented. We looked for a published interval and there is not one. What the test gives you is a direction and a rough order of magnitude, which is genuinely useful, and it does not give you a date.

Why This Is the Answer to a Wear and Tear Denial

Because wear and tear is the most common reason a hail claim gets characterised as something other than a covered loss, and the colour test is evidence rather than argument.

A slope of impacts with black exposed asphalt and sharp fracture edges is describing a recent event. A slope of chalky grey craters with rounded edges is describing something that happened a while ago. Both are checkable, both photograph well, and neither requires anyone to take anyone else’s word for it.

What we do with that is document it. We photograph the impacts with the exposed asphalt clearly visible, annotate what is being shown, and put it in a written scope of work. We are not a licensed public adjuster and we do not negotiate claims. We record what is on the roof.

The Traps in This Test

Three, and an inspection that ignores them is not worth much.

Not every crater is hail. A thermal split, a manufacturing defect and a scuff from a boot all expose asphalt too, and they will all weather in exactly the same way. The colour test dates an exposure. It does not identify what caused it.

Old damage and new damage coexist. A Tulsa roof that has been through two dozen hail events in three years will show both, and the useful question is whether there is a fresh population on top of the old one, not whether the roof has ever been hit.

Shade changes the clock. A slope under a tree canopy oxidises more slowly than one in full sun, so the same impact can read as newer on the shaded side of the same house.

What Changes the Answer

Three variables move how fast the clock runs on a given roof.

Sun exposure

Photo-oxidation is driven by sunlight, so a south facing slope greys faster than a north facing one. Comparing impacts across slopes of the same house needs that allowance.

Roof temperature

We measured a black shingle roof in Bixby at 179 degrees on 8 August 2026 at half past two in the afternoon. A surface that spends its summers there is not weathering on the same schedule as one in a mild climate.

The colour of the shingle

Fresh black asphalt against a dark charcoal shingle is far less visible than the same exposure on a weathered wood or tan shingle, which is a reason to inspect by hand rather than to rely on a photograph from the ground.

Related Questions

What am I looking at in the first place?

A bruise, meaning a circular indentation with a fracture in the mat that feels soft. What does hail damage look like on a roof? covers the full picture and what gets mistaken for it.

Does small hail leave marks that age the same way?

It leaves granule loss rather than mat fractures, and the cumulative effect of that is now measured. Can 3/4-inch hail damage a roof? covers the research on it.

How do I date the roof itself, not the damage?

Measure a shingle. A 36 inch width with a 5 inch exposure is the old three tab format, discontinued around 2008. How old is my roof, and can it still be repaired? covers the method.

See Also

The two answers this one sits between are what hail damage looks like, and how much of it a carrier typically looks for.