What Size Hail Causes Roof Damage? A Complete Guide

One of the most common questions homeowners ask after a storm is whether the hail was large enough to actually damage their roof. The answer depends on several factors, including hail size, roofing material, roof age, and storm conditions. This guide breaks down the relationship between hail size and roof damage so you know when to take action.

The Hail Size Scale

Meteorologists and insurance adjusters use common objects to describe hail size. Here is the standard reference scale:

1/4 inch — Pea sized

1/2 inch — Marble sized

3/4 inch — Penny sized

1 inch — Quarter sized

1.25 inches — Half dollar sized

1.5 inches — Walnut sized

1.75 inches — Golf ball sized

2 inches — Hen egg sized

2.5 inches — Tennis ball sized

2.75 inches — Baseball sized

4 inches — Softball sized

4.5 inches — Grapefruit sized

The National Weather Service classifies hail as "severe" when it reaches one inch in diameter or larger. However, damage can occur at smaller sizes depending on your roofing material and the condition of your roof.

Damage Thresholds by Roofing Material

Not all roofs respond to hail the same way. The type of material on your roof is one of the biggest factors in determining whether hail will cause damage.

Asphalt Shingles

Asphalt shingles are the most common roofing material in the United States and also one of the most vulnerable to hail. Damage typically begins at 1 inch (quarter-sized) hail. At this size, hailstones can knock loose the protective granules on the shingle surface, creating dark spots and exposing the underlying fiberglass mat.

With hail of 1.5 inches or larger, asphalt shingles often sustain cracks, splits, and bruising that compromise the waterproof barrier. Older shingles that have already weathered years of sun exposure are particularly susceptible — they become brittle and fracture more easily under impact.

Metal Roofing

Metal roofs are significantly more resistant to hail damage than asphalt. Cosmetic denting typically starts at 1.5 inches, but functional damage — meaning dents deep enough to compromise the panel integrity — generally requires hail of 2 inches or larger.

Metal roofs rated Class 4 for impact resistance can withstand repeated impacts from 2-inch hailstones in laboratory testing. However, real-world conditions vary, and seams, edges, and fastener points can be more vulnerable than the flat panel surface.

Tile and Slate

Tile and slate roofs offer excellent hail resistance up to about 2 inches. The hard, dense surface of clay tile or natural slate deflects smaller hailstones without damage. However, when hail exceeds 2 inches, tiles can crack or shatter on impact. Replacing individual broken tiles is straightforward, but hidden cracks can lead to leaks that go undetected for months.

Wood Shake

Wood shake roofs are among the most vulnerable to hail damage. Shakes can split, crack, and splinter at hail sizes as small as 1 inch, especially when the wood has aged and dried out. The natural grain of the wood creates stress points where hailstones can cause splits that run the length of the shake, allowing water infiltration.

Flat Roofs

Flat roofs (TPO, EPDM, or built-up roofing) face a unique challenge: hail can puncture the membrane at 1 inch or larger, and because flat surfaces do not shed water as effectively as pitched roofs, even small punctures can lead to significant water damage. Additionally, hail that lands on a flat roof does not roll off — it can sit in ponding areas and cause localized damage.

Factors Beyond Hail Size

The size of the hailstone is important, but it is not the only factor that determines whether your roof will sustain damage.

Wind Speed

Hail driven by strong winds hits with significantly more force than hail falling straight down. A 1-inch hailstone falling in calm conditions might not damage a new asphalt roof, but the same stone driven by 60 mph winds can cause substantial damage. Wind-driven hail also tends to damage one side of the roof more than the other.

Angle of Impact

Related to wind speed, the angle at which hail strikes the roof matters. Steep-pitched roofs may deflect some of the energy from hail, while low-slope roofs take the full impact. South and west-facing slopes often sustain more damage because storms in the central United States typically approach from those directions.

Age and Condition of the Roof

This is one of the most significant factors. A brand-new asphalt shingle roof can handle hail that would devastate the same roof at 15 years old. UV exposure, thermal cycling, and previous storm damage all weaken roofing materials over time. The older your roof, the less hail it takes to cause damage.

Hail Density

Not all hailstones are created equal. Some are solid ice, while others have a softer, slushy core. Solid, dense hailstones cause more damage pound for pound than spongy ones of the same diameter.

When to Get a Professional Inspection

If your area experienced hail of 1 inch or larger, you should have your roof inspected by a licensed professional — regardless of what you can see from the ground. Many forms of hail damage are not visible without getting on the roof and physically examining the shingles.

Even if the hail was smaller than 1 inch, consider an inspection if:

Your roof is more than 10 years old

You have wood shake or flat roofing

The storm included high winds

You can see damage on gutters, siding, or window screens

How HailScore Factors in Your Roof Material

When you check your HailScore, you can select your roof material and age. The scoring algorithm applies material-specific multipliers to account for the different vulnerability levels. A metal roof owner with the same storm history as an asphalt shingle owner will receive a lower risk score because their roof is more resistant to damage.

This gives you a more accurate picture of your actual risk — not just how many storms have hit your area, but how likely those storms are to have damaged your specific roof.

Check your HailScore for free — enter your address and roof type to see your personalized storm damage risk score. It takes 10 seconds and does not require any signup.