Fire resistance and safety are some of the predominant factors people consider when selecting roofing tiles for homes, businesses, and other buildings. To ensure reliability and quality, roofing tiles undergo certification processes that assess their performance in various aspects, including fire resistance, durability, and adherence to quality standards.
But what do tile ratings and certifications mean?
During the certification process, roofing tiles are subjected to standardized fire tests that evaluate their ability to resist flame penetration, flame spread, and the generation of embers. Additionally, durability and quality aspects are addressed, such as resistance to weather conditions, impact resistance, and the ability to withstand freeze-thaw cycles. These certifications give homeowners, builders, and architects confidence that the roofing materials they choose meet the necessary criteria for reliable and long-lasting performance.
Fire Resistance of Roofing Tiles
To obtain fire rating certifications for tiles, rigorous testing procedures are carried out in compliance with the mentioned standards. Controlled fires are applied to one side of each partition, subjecting the clay tiles to specific temperatures and durations.
The fires approximate temperatures of 1,000℉ (538℃) for 5 minutes, 1,300℉ (704℃) for 10 minutes, 1,550℉ (843℃) for 30 minutes, 1,700℉ (927℃) for 1 hour, and 1,850℉ (1,010℃) for 2 hours.
The tests continue until specific conditions are reached, including fire damage allowing the passage of flame or gas at a temperature sufficient to ignite cotton waste or transmitting heat through the partition causing temperature increases on the unexposed surface or at specific points.
Fire Resistance ratings
These stringent tests and resulting certifications demonstrate the capability of tiles to withstand prescribed fire conditions. They ensure the tiles’ fire-resistant properties, contributing to structures’ overall safety and protection.
Roof Tile Fire Ratings
|A||Tiles are effective against severe fire test exposures. Roofing materials classified as Class A are generally non-combustible, capable of enduring intense fire exposure, and do not generate firebrands.|
|B||Tiles are effective against moderate fire test exposures. Class B roofing consists of combustible materials treated with fire-retardant chemicals to enhance fire resistance properties.|
|C||Tiles are effective against light fire test exposures. Class C roofing primarily comprises materials such as untreated wood shakes and shingles, which are more susceptible to fire damage and can only withstand light levels of fire exposure.|
Water Resistance of roofing tiles
Given the diverse conditions to which waterproofing may be exposed, no single test can comprehensively evaluate performance across all exposures. Therefore, not all tests will be necessary for specific evaluations. Among the historically widely used testing methods for horizontal membranes are spray testing, flood testing, capacitance (impedance) testing, nuclear metering, and infrared thermal imaging. These methods utilize electricity and electric circuits to detect and identify potential issues in roofing and waterproofing systems, commonly referred to as “Low Voltage Electrical Conductance Testing” and “High Voltage Spark Testing.”
Water Resistance classifications
Roofing tiles are categorized into three classes based on their maximum water absorption thresholds. These classes provide valuable information regarding the tile’s ability to resist water penetration. The classification system helps determine roofing tiles’ level of protection and durability in various environmental conditions.
Tile Ratings and Maximum Water Absorption
|Weight Classification||W = Oven Dry Weights of Tile (lb/ft3)||Max. Water Absorption lb/ft3 – (kg/m3)|
|Class I||W < 105||18 (288)|
|Class II||105 < W < 126||15 (240)|
|Class III||W > 126||13 (208)|
Freeze-thaw classification of roofing tiles
For a roofing material to be available in areas subject to frequent freeze-thaw cycles, it must meet certain requirements. A test is conducted by exposing the product to freezing temperatures of approximately 14℉ for 24 hours and then allowing it to thaw at room temperature for 24 hours. The sample is then placed at a higher temperature of approximately 113℉ for 24 hours and then at room temperature again for 24 hours.
If no significant changes are observed after three cycles of freeze-thaw testing, the product is considered suitable for such climate regions.
Freeze-Thaw Classification (ASTM rating)
|1||Providing resistance to severe frost action – 500+|
|2||Providing resistance to moderate frost action – 50 to 500|
|3||Providing negligible resistance to any frost action – less than 50|
Impact Resistance of roofing tiles
An impact resistance test, FM 4473, or the industry standard hail impact resistance test, involves ice balls of various diameters being launched at 71.6 miles per hour at a test wall of roof tiles. The test is meant to simulate the impact energy of an actual hailstone. This test simulates the worst-case hailstone scenario since the ice balls are generally harder and denser than hailstones. For the product to pass, the tile must not show any evidence of visible cracking or breakage.
|1||Tile can withstand impact from a 1 ¼” ice ball.|
|2||Tile can withstand impact from a 1 ½” ice ball.|
|3||Tile can withstand impact from a 1 ¾” ice ball.|
|4||Tile can withstand impact from a 2” ice ball.|
Wind resistance of roofing tiles
The wind resistance of roofing tiles determines their ability to withstand the forces exerted by wind, which is a high priority in areas with high wind speeds like tornados and hurricanes. The mechanical uplift resistance of the tiles, when installed according to the manufacturer’s instructions using approved attachment systems, plays a significant role in their wind resistance. However, it is important to note that simulating natural wind conditions with different intensities, durations, and turbulence is beyond the scope of testing methods.
One testing method used to evaluate the wind resistance of roofing tiles is High Wind Testing. It involves installing a test wall of tiles in front of a wind simulator capable of generating wind speeds of up to 180 miles per hour. The response and resistance of the tiles to various wind forces and speeds are then assessed.
Two important standards for wind resistance testing of roofing products are ASTM D3161 and ASTM D7158. ASTM D3161 measures the ability of steep slope roofing products, such as shingles, to withstand fan-induced wind speeds. It assigns them classifications (Class A, Class D, Class F) based on their performance at specific wind speeds.
Various wind resistance tests are available for roofing tiles, including ASTM C1568, ASTM C1569, and ASTM C1570, which evaluate the wind resistance of concrete and clay roof tiles using different methods. Testing Application Standards (TAS) provide procedures for testing the performance of tile roof systems, including TAS 100, 101, 102, 102A, 108, 110, and 112.
Other standards and tests, such as UL 580 and FM-4471, provide classification and ratings for the uplift resistance of roof assemblies and panel roofs, respectively, based on their performance under specific wind conditions.
Wind Resistance Classifications
|Wind Speed Resistance|
|Class||Wind Speed MPH|
|A||Can withstand winds up to 60 MPH.|
|B||Can withstand winds up to 70 MPH.|
|C||Can withstand winds up to 80 MPH.|
|D||Can withstand winds up to 90 MPH.|
|E||Can withstand winds up to 100 MPH.|
|F||Can withstand winds up to 110 mph.|
|G||Can withstand winds up to 120 MPH|
|H||Resist uplift at wind speeds up to 150 mph.|