Impact Resistant Shingles
Impact resistant shingles and roofing materials can be applied to both commercial and residential buildings. In Texas, this option can greatly increase the protection from hail and storm damage. Texas has two storm seasons and remains one of the hardest hit storm damaged areas in the mid-west. 911 Exteriors understands this unique option and helps homeowners select products that better protect their investments.
Hail is by far the single greatest threat in Texas. And, every year Texas receives at least some hail damage. This is unique to the mid-west. When hail hits an asphalt roof, it knocks off a lot of the granule that protects the roof. Also, the edges of shingles may get damaged. And if the hail penetrates the shingle, roof leakage may occur.
Are impact resistant shingles worth the money?
Impact resistant shingles are designed specifically to mitigate damage from severe weather, such as hail and wind damage. Each product has an impact resistant of at least Class 4 (UL) and window resistance. This will result in less damage over asphalt shingles. And, insurance companies will often apply a discount on homeowner policies if the home has impact resistant shingles.
Luckily, specialty roofing materials are very abundant and combine the look of traditional shingles with the added benefits of impact resistance. For example, wood shake shingles can be found in a new, impact resistant version. This allows the homeowner to have the look of wood shake shingles but using a stronger, better material. Prices can be higher but the benefits can often offset the price difference.
How are they manufactured?
There are many manufacturers that offer impact resistant shingles in a variety of styles. For example, you can find traditional asphalt shingles, wood shake shingles and other popular styles. Each shingle is designed to better withstand impacts and wind. And, each shingle can use a different method to attach granules to shingles (if granules are used) and processes to prevent shingles breaking. Each product must meet specific specifications in order to be classified as impact resistant.
Standard for Impact Resistance of Prepared Roof Covering Materials
UL 2218 explains how materials are tested and certified. According to the The Blueprint for Safety (blueprintforsafety.org):
The most effective way to minimize hail damage is to use roofing materials that are resistant to hail impacts. In 1996, the first test standard was developed to assess the impact resistance of roof coverings – UL 2218 Impact Resistance of Prepared Roof Covering Materials. Subsequently, an additional test standard, FM 4473, Specification Test Protocol for Impact Resistant Testing of Rigid Roofing Materials by Impacting with Freezer Ice Balls, was developed. UL 2218 is intended primarily for testing flexible roof coverings, but has also been used to test rigid roofing materials. FM 4473 was developed specifically for testing rigid roof coverings. FM 4473 defines rigid roofing materials as those manufactured as tiles or planks from slate, concrete, or clay materials.
How Materials Are Tested
So, how are these materials actually tested?
The UL 2218 test standard uses steel balls ranging from 1.25 inches to 2.0 inches in diameter. The steel balls are dropped from heights of 12 feet for the 1.25 inch ball to 20 feet for the 2 inch ball. Although this apparatus tests for impact resistance, not hail resistance, the impact of the steel ball simulates the impact energy of free-falling hailstones. The test assembly is struck with the steel ball twice in the same location on the assembly. To meet the acceptance criteria of UL 2218, the roof covering material exposed surface, back surface and underneath layers must show no evidence of tearing, fracturing, cracking, splitting, rupture, crazing or other evidence of opening of the roof covering layer. Qualifying assemblies are given a class rating depending upon successful performance of the assembly under impacts from the varying sized steel balls.
What Makes Roofing Materials Impact Resistant?
They go on to specify how different types of materials are tested and how they can be made more resistant.
Even though most of the common roofing systems used today can be altered or modified for increased impact resistance, the features that make a roofing product impact resistant vary depending upon its material type. Wood shingles and shakes can be made more impact resistant by increasing their thickness and density. Such alterations make them less prone to splitting, which is the primary mode of failure after an impact. Metal roofing can be made more impact resistant by increasing the thickness or the stiffness of the material. Metal 26 gage and thicker will pass the UL 2218 impact test at a Class 4 level. In addition to thickness, metal becomes much stiffer when it is bent or seamed. The fact that some of the metal products are made to look like wood shakes, tile, or slate means the metal has been stiffened considerably just through the forming process.
Are All Products Tested?
Only products that wish to be classified as impact resistant are tested. However, any material may be tested including specialty materials.
Alternative products, such as synthetic tiles, are generally made of either flexible material, such as rubber, or more rigid materials such as plastic, wood fiber, urethane, and recycled resins. These alternative materials can usually be manufactured to attain a Class 3 or 4 UL 2218 rating. Asphalt shingles manufactured with polymer-modified styrene-butadiene-styrene (SBS) or atactic polypropylene (APP) are more impact resistant than typical composition shingles manufactured using a glass fiber base mat or organic felt. The SBS or APP is blended into the asphalt to enhance flexibility, durability, crack resistance, impact resistance, and resistance to ultraviolet light. These and other modifications have enabled asphalt shingles to make the transition from being one of the most vulnerable roofing systems to one of the strongest choices available.
For more information on UL2218, click here.
The professionals at 911 Exteriors are trained and can help consumers select the proper materials for extreme Texas weather conditions.