What Size Hail Will Damage a Roof? (Sloped, Flat…)

When a storm rolls through, the first question on many property owners’ minds is: what size hail will damage a roof? The answer depends on your roofing system, the slope of your roof, and the materials in place. While small hail might leave cosmetic damage on a residential asphalt roof, it can wreak havoc on a flat commercial roof with a TPO or EPDM membrane.

Hail damage is one of the most costly weather-related roofing issues in the U.S. Here’s what you need to know:

• Material matters: Hail affects different roofing materials in different ways.
• Size and speed of hail: The bigger and faster the hail, the more severe the damage.
• Roof pitch and age: Flat and older roofs are more vulnerable to hail impact.

Let’s break it all down and help you protect your property—residential or commercial—before the next storm hits.

⛈️ How Hail Size Impacts Roof Damage

Not all hail is created equal. The size of hail directly influences the level of destruction it can cause to your roof.

Understanding Hail Sizes

Hail is measured in diameter and compared to familiar objects:

• Pea-sized (¼ inch): Typically won’t cause structural damage but may wear down shingle granules.
• Marble-sized (½ inch): May start to dent soft roofing materials or thin metal.
• Quarter-sized (1 inch): The tipping point for potential damage to most asphalt and single-ply membranes.
• Golf ball-sized (1.75 inches): Large enough to puncture TPO roofing and dent metal panels.
• Baseball-sized (2.75 inches and larger): Can shatter skylights, crack roof decks, and tear membranes apart.

Key Thresholds for Residential and Commercial Roofs

• Asphalt shingles: Damage often begins around 1 inch hail.
• Metal roofs: Dents can occur from 1.5-inch hail and up, though structural damage is rare.
• TPO or EPDM roofing: Vulnerable to punctures from hail 1 inch or larger, especially when aged.
• Built-up roofing systems (BUR): May resist light hail, but larger hailstones can damage the top layer or cause membrane fractures.

🏠 Residential Roofs vs. Commercial Roofs: Different Risks

Residential and commercial roofs have different slopes, materials, and construction styles, all of which affect how hail causes damage.

Residential Roofs: Sloped and Shingled

Sloped roofs on homes often use asphalt shingles, metal, or composite products. While sloped surfaces help hailstones glance off rather than land directly, damage still occurs with large enough hail.

• Granule loss: Even small hail can wear off shingle granules, shortening the roof’s lifespan.
• Bruising and cracking: Hail can break the fiberglass mat inside shingles, leading to hidden leaks.
• Flashing damage: Metal flashings around chimneys and vents are prone to dents and loosening.

Commercial Roofs: Flat and Vulnerable

Commercial roofs are typically flat or low-slope and rely on waterproof membrane systems like TPO, EPDM, or modified bitumen. These systems are more directly exposed to the vertical impact of hail.

• TPO roofing: Durable but can crack or puncture under larger hail, especially if the membrane is thin or aged.
• EPDM roofing: Rubbery and flexible, but prone to punctures or uplift around seams from hail larger than 1 inch.
• Warehouse roofing systems: Often feature large, exposed roof surfaces with rooftop units (HVAC, skylights) that are highly vulnerable.
• Drainage systems: Flat roofs rely on well-designed drainage. Hail can clog or damage these systems, leading to ponding and leaks.

❗️ Other Factors That Affect Hail Damage

The size of the hail isn’t the only thing that determines whether your roof will take a beating. Several other factors come into play during a hailstorm.

Roof Age and Condition

Older roofs are more brittle and more likely to fail under hail impact. This is especially true for both asphalt shingles and commercial membranes.

• Residential shingles: Granules thin out and shingles become more prone to cracking with age.
• Industrial roofing systems: UV exposure degrades the flexibility of TPO and EPDM membranes, making them easier to puncture.

Hail Speed and Density

The velocity and hardness of the hail matter just as much as its size. Dense, fast-falling hailstones will do more damage than lighter ones.

• Wind-driven hail: Can strike at an angle and cause shearing or tearing damage to membranes or lifted shingles.
• Multiple strikes: Repeated impact in one area weakens material quickly, even if each hailstone is relatively small.

Roofing System Quality

Thicker membranes, reinforced underlayments, and impact-resistant shingles all improve your chances of withstanding hail.

• High-performance TPO systems: Some commercial-grade TPO membranes are designed to resist hail puncture better than standard grades.
• Impact-rated shingles: Class 4 shingles on residential homes hold up better under severe storms.

⚠️ 5 Signs of Hail Damage on Commercial Roofs

Flat commercial roofs don’t always show obvious signs of damage from the ground. Here’s what to look for after a storm.

1. Membrane Punctures: Look for small, dark circles or visible holes in the membrane surface.
2. Crushed Insulation: Impact may not break through the membrane but can compress insulation underneath, affecting R-value and support.
3. Damaged Flashing: Hail can dislodge or dent metal flashing around HVAC units, skylights, or walls.
4. Water Ponding: Post-storm ponding often points to clogged drains or indentations caused by hail impact.
5. HVAC and Rooftop Unit Damage: Dents, fan damage, or broken components are common indicators of hail impact.

📋 What To Do After a Hailstorm

Once the skies clear, timing is everything. Whether it’s your home or a commercial facility, acting quickly helps prevent long-term damage.

Residential Action Steps

• Inspect visible areas: Look for loose shingles, gutter dents, or granules in downspouts.
• Take photos: Document everything for your insurance claim.
• Schedule a roof inspection: Have a professional check for hidden damage and make temporary repairs.

Commercial Response Plan

• Conduct a rooftop inspection: Use qualified commercial roofing experts to assess the surface.
• Check rooftop units and drainage: Hail can damage or dislodge rooftop units and clog drain systems.
• Contact your insurance provider: If you notice damage, get the claim process started early.
• Request a commercial storm damage assessment: A professional roofing contractor will help you determine whether repairs or a full replacement are necessary.

💪 How To Prevent Future Hail Damage

While you can’t stop hail from falling, you can prepare your property to minimize damage when it does.

• Upgrade materials: Opt for impact-resistant shingles or reinforced TPO membranes when replacing your roof.
• Regular maintenance: Clean gutters, repair seams, and maintain rooftop units to keep your system in top shape.
• Add protective barriers: Install screens or guards over vulnerable HVAC units and skylights.
• Get annual inspections: Proactive maintenance helps spot early signs of wear that hail can worsen.

🤝 Trust Embry’s Roofing for Residential and Commercial Storm Damage Solutions

When it comes to hailstorms, knowing what size hail will damage a roof is just the beginning. From sloped residential roofs to flat commercial systems like TPO and EPDM, every property has unique vulnerabilities. Embry’s Roofing understands the demands of both residential and industrial roofing and has years of experience navigating commercial storm damage.

If your home or commercial facility has been through a hailstorm, don’t wait for leaks to appear. Let our expert team inspect your roof, provide honest feedback, and offer solutions that last.

Contact Embry’s Roofing today for a free hail damage inspection and repair estimate, because your roof deserves expert care.