What Are the Effects of Hail on a Composite Asphalt Shingle Roof?

by Feb 5, 2019

Hailstones are among the most destructive natural events your composite asphalt roof can experience. Falling hailstones can dislodge the small granules that protect the water-shedding asphalt and fiberglass layers below, crack the material, or dislodge shingles – all of which lead to leaking.

Relative to other roofing materials, like slate, metal, or synthetic shakes, composite shingles are not as resistant to large impacts. However, asphalt shingles are cost effective and more readily replaceable, making them the most common roofing material used in the US today, found on over 80% of homes.

Composite asphalt shingles are also affected by temperature, becoming brittle at low temperatures. Hailstones striking a very cold (or old, which also causes brittleness) may actually fracture or break the shingle. Luckily, this is often offset in cold temperatures by the presence of snow, which softens the impact of hailstones and in general make winter hailstorms less destructive than summer hailstorms.

Summer hail storms tend to be the most destructive to asphalt shingles by dropping hail and rain simultaneously. Rain can wash away lost granules immediately, exposing the mat and asphalt to both UV light and moisture.

We have a more detailed article on how composite asphalt shingles are constructed, but for the purposes of understanding the basic layers and terminology of a shingle, this illustrates the main components:

Asphalt shingle layers diagram illustration_Rhoden Roofing

Asphalt shingle layers diagram illustration: Rhoden Roofing, Wichita, Kansas

The base mat (nowadays almost always fiberglass) combined with asphalt coating make up the water shedding ability, and are protected from the sun, abrasion, and impact by the surface granules. Asphalt shingles are designed to be water-shedding, not waterproof. This is important to note because when granules are removed, water will not move as quickly over the shingle’s surface, allowing for more opportunities for water to find it’s way through the mat or between the rows (called “courses”) of shingles and into the home as a leak.

How Do I Know If My Composite Shingles Have Hail Damage?

The following are typical items that inspectors, insurance adjusters, or roofing contractors look for to evaluate if a roof has experienced hail damage. Most often, damage can be seen as indentations and/or fractures on the shingle’s surface. Hailstones vary in size, shape, and hardness and create a random pattern of dents or depressions.
Be sure to take appropriate safety precautions while assessing your roof!
  • Granule Loss. At points of impact, granule loss may be accompanied by a surface depression. Loss of mineral granules either as an immediate or gradual consequence of storm damage can lead to the asphalt coating being directly exposed to ultraviolet rays and accelerate the aging of the shingle. This may lead to accelerated aging of the shingle. Therefore, even with no current damage to the layers beneath, granule loss is not just cosmetic damage. “Sugaring” — an old-school process of adding loose granules to damaged shingles with asphalt cement — is not a permanent solution.
  • Crushed Granules. The protective granules that surface asphalt shingles are a mix of crushed rock, ceramic, and other materials (coloration, microbial defense, etc. depending on the product). One thing to look for with hail damage are small light-colored dots that appear consistently across the entire roof. The lighter color is from crushed ceramic granules. Concurrent rain often washes the lighter/white powdery crushed material away, but when present it is an obvious sign of hail impacts.
  • Cracks in the Asphalt Surfacing. These may radiate outward from points of impact, or appear in a ‘shattered’ pattern. Horizontal linear cracks (parallel to the ground) may be also present if high winds lifted and bent the shingles back. In either scenario, if you see cracks across the surface, the water-shedding coating on the shingle is compromised and should be replaced.
  • Exposed Fiberglass Mat. This is the more extreme version of cracks in the asphalt surfacing. In this case, shattered granule-asphalt surfacing has actually broken free and exposed the fiberglass mat underneath. Sometimes you will also see fractures or tears in the fiberglass mat radiating out from the points of impact. As the fiberglass layer of a shingle provides its tensile strength, even small tears in the fiberglass dramatically increase the risk of shingle tearing in the wind. When you see ripped or partial shingles on a roof, this is what it started as.
  • Loosening of the Self-Seal Strip. This damage may or may not be immediately visible and may weaken the seal integrity, creating the possibility of future shingle blow-off. When the sealant of a shingle is damaged, the shingle will become loose, which will eventually allow them to catch the wind and fall off, or cause the shingle to tear as it is no longer held tightly in place. Crooked or misaligned shingles are often the first symptom that the self-seal strip has been compromised. Later, shingles will come loose entirely, and a common phone call we get is from people who find shingles in their yard while mowing the lawn.
  • Damage to Flashings and Soft Metals. Even if damage is not visible on the shingles themselves, look for indentations on metal flashings, gutters & downspouts, A/C fins, or chimney caps. If hail was substantial enough to damage the metals, there may be damage on the shingles as well that will take some time to show. Hail damage may not appear on the shingles immediately after a storm, but over time, clusters of granules may come off at the point of impact in a random pattern and expose the mat layer below.


What Factors Make a Roof More Susceptible to Hail Damage?

  • Older roofs. As shingles age, they become more brittle, making them more susceptible to impact. Older shingles also naturally lose some of their granules, allowing UV radiation to degrade the asphalt and fiberglass underneath.
  • Older style decking, such as plank decking, or space (also called “skip decking”) decking from the era when cedar roofs were common. Hail hits along decking seams are more likely to crack shingles given, and even more so in the case of actual decking gaps (like with space decking). If your home/building was built before the 1980s and the roof decking has not been resurfaced, it is much less common that you have solid decking (OSB or plywood).
  • Existing heat damage, cupping or curling. If the condition of the roof was poor to begin with, a hail storm can be especially destructive. Heat damaged shingles tend to curl up on the edges, and these edges can break off during a hailstorm. When the corners of a shingle are missing, winds can more easily lift the shingle and allow or push water underneath in a driving rain.
  • Thin or 3-tab shingles. Shingles come in different styles, qualities, and thicknesses. Three-tab shingles are thin, flat, and provide the least amount of impact resistance. Dimensional and architectural (also called ‘laminate’) composite shingles are heavier, thicker, and offer better protection from hail damage. We have more info about the different types and styles of asphalt shingles in a separate article.


Does Hail Damage Always Mean the Roof Needs To Be Replaced?

No. Simply having hail on an asphalt shingle does not necessarily mean the roof will need to be replaced. There are several factors to consider when evaluating the roof for hail damage. If the damage conditions above are not present, the roof is likely in fine shape, but do monitor that nothing changes over the next 30 days or so, as granule loss in particular can take time to show up.

The first consideration is the age of the roof.  Newer shingles can absorb hail impacts better as the asphalt has not become as brittle and broken down over years in the elements.  A solid roof deck compared to one that has space or skip decking decreases the likelihood of fracturing on the shingles.  The temperature at the time of hail also plays a factor.

What Size Hail Usually Causes Roof Damage?

As a general rule, hail needs to be at least one inch in diameter, or quarter sized, to cause enough damage to consider replacement. This is a only a rough guideline, as type/age/condition of roof vary in their susceptibility. However, damage is certainly possible from 1-inch hailstones on up, so if you experience a storm with hail beyond that threshold would certainly warrant inspecting for damage.

Additionally how hard or soft the hailstones are makes a big difference – think ‘clumped snow’ vs ‘pure ice.’ The angle of the hail impact also makes a difference. Having hail strike the roof at closer to a 90-degree angle to the roof slope will case a direct impact, which is more damaging than a deflecting blow. You can often see the effect of this by comparing the impact of hail strikes on different slopes of a roof after a storm if the winds came consistently from one direction.

Can Asphalt Shingles Be Repaired After a Hailstorm?

No, individual shingles cannot be repaired or restored after hail damage.

Individual shingles can be replaced (if matching, compatible materials are available). In general, however, this is not a feasible solution for hail damage. Hail usually impacts many (if not most) shingles across an entire roof; or at a minimum, entire slopes of a roof. Replacing individual shingles is a labor-intensive job that requires skillfully manipulating to safely remove damaged shingles while preserving those around/ overlapping it and the underlayment below. This describes the process used for repairing individual site damage – for example when a branch falls through a roof – but is not cost-effective for hail damage repairs.

Roofs are sometimes repaired with “partial replacements,” where individual roof slopes are replaced. This is uncommon, but sometimes a storm has consistent wind such that only west-facing slopes, for example, have hail damage, or perhaps trees or surrounding buildings sheltered the majority of a roof from experiencing damage. When individual slopes are replaced, building code requires re-shingling 2 feet beyond roof hips and ridges to properly interlace courses (rows) of shingles.


Do Leaks Always Appear Right Away After Hail Damage?

No. In fact, it is uncommon to find leaks from new damage within the first few days. However, minor leaks first impact decking and fascia boards. By the time water makes its way through decking, insulation, and/or attic spaces and causes staining on living space drywall, the roof may have been leaking for weeks.

Even if hail damage does not mean immediate leaks into the home, the effects of damage can compound from continued weather from continued weather will be detrimental to the roof. Failure to address potential hail damage at the time of the event could also result in insurance carriers not properly paying for damage after an extended period of time. The majority of roofing companies do not charge for a simple inspection, so best practice is to always have a reputable company come out soon after any hail event.

Hail damage can involve working with insurance adjusters, suppliers, and installers. Rhoden Roofing employs roofing experts that can work with your adjuster to make sure claims are processed quickly and to your satisfaction. If you are in the greater Wichita area, click here to get your questions answered by a local roofing expert.


Updated November 2022. Rhoden Roofing, LLC

Latest Posts