The roof damage due to hail in Oklahoma is dependent on a few factors. The physics of the strom, what materials were used for the roof and those materials have aged between two consecutive storms determine how the roof will be damaged. The interplay between these factors explain why some roofs fail fast and others last longer. Oklahoma is situated in a high-risk area with regular hail storms which results in a damage pattern that is different from other regions with lower risks. You won’t see damage from hail immediately, instead it starts degrading the materials that become bad over time.
Oklahoma is in the middle of warm and moisture rich air from the Gulf of Mexico and dry air descending from the Rockies. This collision of air fuels supercell thunderstorms capable of producing large hail with dense and layered ice cores.
Supercell updrafts take these hailstones through freezing layers which increase the size and density of hail. Even the hailstones with moderate diameter in Oklahoma carries higher impact energy than hailstones of similar size in other places.
The unpredictable pattern of strom only increases damage. The hail storms move in oblique angles due to the powerful horizontal winds. As a result, hail strikes the roof unevenly, damage is concentrated on windward side while the leeward side is almost unaffected.
The temperature also change rapidly after storm. Oklahoma can experience daily change in temperature to the extent of 30 to 40 degrees. This kind of temperate change expands the microfracture created by hail and worsens the damage which makes even minor impact damage cause roof failure over a season or two.
Size is only one factor in hail damage, functional damage occurs when the energy of impact exceeds the capability of the roofing material to absorb and redistribute the force.
Asphalt shingles are the most common type of roofing material used for residential houses in Oklahoma. They are also cause for majority of heat-related failures.
Each shingles are made of fiberglass or organic mat saturated with asphalt and coated with mineral granules. This layers system is affected by hail through multiple mechanisms.
Hail removes the mineral granules from the surface of the shingle and produces the following:
These granules work as sacrificial UV shields and once they are gone, the asphalt oxidizes fast, becomes brittle, and loses flexibility. This speeds up cracking even when there is hail damage without leaks.
If the impact is powerful, it can crush the mat inside. These areas feel soft or spongy and they appear darker than the surrounding material.
If the mat is fractured, the load distribution and water shedding is disrupted, and over time wind movement and change in temperature cause these weak areas to break allowing water to enter the homes.
Even if the storm is under the threshold, continuous exposure to hail weakens shingles, and when you get even a moderate storm later, you will see sudden roof failure event though no single storm appeared big enough to damage your roof.
The combo of hail and wind can break the adhesive bonds used to seal shingles together, which will allow shingles to life easily in later storms, exposing the seams and nail penetrations to direct contact with water.
The shingles might seem fine, compromised seals rude the wind resistance of the materials and their long term performance.
Not every circular mark is hail damage.
Professional inspectors with enough experience can under the difference with feel, fracture behavior, and distribution instead of using just its appearance to determine.
Hail usually fractures tile, slate, and concrete roofing materials instead of deforming it like metal.
Metal roofs in Oklahoma has multiple parts including standing seam panels, exposed fastener panels, and specialty profiles. Hail causes mechanical deformation instead of material loss.
Hail impacts on metal panels causes dent, and these micro depressions retain moisture and debris. These dents speeds up coating degradation and corrosion even if the remaining of the roof is fine. The exposed fasteners are especially vulnerable due to repeated impacts and change in temperature. It can loosen the fasteners or elongated their holes creating a delayed leak points.
The protective coating and paint is in the risk of being fracture by hail and exposing bare metal. Corrosion spreads laterally and the damage to the area expands once the coating is gone, even if the outside looks well finished. The initial hail damage to metal may look to be cosmetic, but the long-term performance is greatly compromised if the coating breach is not addressed.
Commercial structures and some residential houses use roof materials with low slopes, like TPO, PVC, EPDM, and modified bitumen.
Large hail punctures membranes directly or compresses insulation under the membrane. When an insulation is bruised, they deform under load and creates depressions where water gets collected.
And this collection of water increases the explore of the roof to UV rays and thermal stress which speeds up the aging of the membrane and seam failure.
Hail impacts near seams, terminations, and penetrations can:
Seam integrity is important for roofs with flat top and localized hail damage can produce uneven consequences.
The combined interaction of hail, wind, and temperature is the most damaging factor for roofs in Oklahoma.
Once the roof has impact damage, the rapid change in temperature continuously expands and contracts the microfractures in shingles, underlayments, and decking.
It shows why roofs that seem fine and manageable right after a strom develops leaks down the line.
Many hail-related failures are concealed.
Shingles may bounce from hail impact but wood decking and underlayments absorb the impact shock. The fasteners may get loose if there are microfractures in decking which will allow water to enter in the layers of your roof materials.
You will usually see damage to metal vents, pipe boots, skylight frames, and chimney flashing before you see damage to the primary roof coverings. These fixtures can cause leak early.
Your drainage, pipes, and window seals may take damage from hail. It can alter the water flow pattern and contribute to water leaking into the roof and walls.
Age of the roof significantly affects hail resistance.
Impact-resistant shingles distribute the impact energy better but are not immune to granule loss or cumulative damage.
Your insurance claim for hail is evaluated differently based on the age of the roof and the class of material. Two roofs under the same strom can get different coverage outcomes due to preexisting condition assessments.
Understanding how hail damages roofs informs better decisions whether to go for roof repair in Oklahoma or roof replacement in Oklahoma.
