Hail Resistance Of Fiberglass Shingles

Hail Resistance Of Fiberglass Shingles

Sep 29, 2013

Fiberglass shingles have become popular among items to use when it comes to decorating all sorts of buildings. However, they have also been known to struggle to stay intact when hail storms occur. This can cause expenses to homeowners and insurance companies, thus forcing many insurance companies to look into what is causing this problem to occur.

Fiberglass shingles have been used on properties for nearly forty years. A study from the Roofing Industry Committee on Weather Issues found not long afterwards that UL 2218 Class 4-rated shingles can resist damages from hail. Class 4-rated shingles are highly rated as they can simulate impacts from 2-inch-thick bits of hail.

A 2011 study was performed to determine how fiberglass shingles can wear out. It was found upon reviewing fiberglass shingles with Class 4 ratings were able to resist hail damages at a better rate. This was observed after a hail event occurred in Texas and impacted surfaces with these shingles on them.

How are Damages Measured?

It is unclear as to how damages can be measured because everyone has different ideas of what constitutes as hail damage. Hail damage can entail visible damages to shingles for the most part including cases where granules will fall off. Sometimes the loss of the ability of shingles to handle water or the ability of shingles to stay intact can constitute as damages to the area.

Measurements in the Study

A new study was created to analyze hail resistance on these shingles. Sixteen shingles were acquired with six being laminates and five being three-tab modified fiberglass shingles while five aged shingles were also used. Five of these shingles met UL 2218 Class 4 standards as mentioned earlier. The following were used as measurement standards for all these shingles:

Net mass was measured based on how much weight they contained. These included weights from 73.5 to 128.3 pounds for every 100 feet.

Desaturated mat weight, or the weight after asphalt and granules are removed with a solvent and then oven dried, was also used to see how the base acts. The weights were from 1.62 to 2.21 pounds per 100 feet.

Granule adhesion was measured as a means of seeing how much granule loss is accepted for every gram of weight. The granule losses were estimated at levels of 0.55 to 0.67 grams but two that were aged or exposed were at 1.84 grams and did not comply with the requirement for the study.

Tear resistance was reviewed to see how strong the tiles are and if it would take a while for them to tear. Most of the new shingles met the 1,700 gram requirement but the five aged and exposed shingles did not.

Tensile strength or the ability of the shingles to stay intact over time was also measured. The modified asphalt shingles had an average tensile strength of 110.9 pounds per inch while the aged ones came in at 87.66 pounds per inch.

Test Observations

Ice spheres ranging from 1 to 2 inches in diameter were shot out at speeds of up to 72 mph at these shingles to simulate hail. It was found that more granules are lost when larger sphere come about but modified shingles with adjusted asphalt surfaces ended up being easier to use. However, UL Class 4-rated shingles with fiberglass materials lost only a third of the granules than what nonrated shingles had on average.

The angle that the shingles were situated at did not make much of an impact at all. Shingles that were at a 45-degree angle responded in the same was as shingles at a 9-degree angle for the most part.

In addition, tile fractures were uncommon in these Class 4-rqated shingles. They didn’t even fracture from the 2-inch ice pellets.

What the Results Mean

There are many things that can be found from this study:

Modified shingles with some fiberglass materials will be more resistant to some problems. UL-rated shingles will lose fewer granulates and won’t tear easily. A shingle roof with a better tensile strength will last longer. Older shingles are weaker and more likely to wear out and should be replaced.


The best thing for companies that make fiberglass shingles to do is to test their products to see if they can meet UL standards while creating warranties for their products based on how much damage they can handle. Shingles must be appropriately modified to reduce their damages in hailstorms.


Koontz, J. D. & White, T. L. (2013). A Study with Impact: Determining the hail resistance of fiberglass shingles. 2013 International Roofing Expo Reports.

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