Who Sets Roof Fire Rating Requirements in Texas?
Roof fire rating requirements in Texas are not set by a single statewide authority. Instead, they're established through a combination of national codes, testing standards and local jurisdictions.
International Building Code (IBC) and International Residential Code (IRC)
Most Texas jurisdictions adopt versions of the International Building Code (IBC) and International Residential Code (IRC). These codes:
- Define when fire-rated roofing is required
- Specify minimum fire classifications (Class A, B, or C)
- Link required ratings to building type, occupancy and location
For example, IBC Table 1505.1 outlines the minimum roof fire classification based on construction type.
Local governments in Texas cities, counties or authorities having jurisdiction (AHJs) adopt and enforce these codes, sometimes with amendments.
Local Building Codes and Fire Codes
In Texas, local building departments and fire marshals enforce code compliance. They may:
- Require higher fire ratings in dense developments
- Apply additional rules in wildfire-prone areas
- Enforce spacing requirements between structures
Ultimately, the local authority having jurisdiction determines what roof fire rating is required for a specific project.
National Testing and Standards Organizations
While building codes define requirements, they rely on standardized testing methods developed by organizations such as:
- ASTM International
- Underwriters Laboratories (UL)
- FM Approvals
These organizations create and maintain the test procedures that are used to determine a roof’s fire rating.
Roof Fire Rating Classifications
Roof coverings are classified into three primary rating groups based on their performance during the tests above.
Class A Roof Rating (Highest Protection)
- Effective against severe fire exposure
- Offers the highest resistance to flame spread and penetration
- Often required for high-risk applications or wildfire-prone areas
Class A roofs can typically be used wherever Class B or C is required.
Class B Roof Rating (Moderate Protection)
- Effective against moderate fire exposure
- Common for mid-level risk buildings
Class C Roof Rating (Basic Protection)
- Effective against light fire exposure
- Provides minimal fire resistance
Unrated Roofs
- Do not meet minimum standards
- Generally not permitted under modern building codes
How Roof Fire Ratings Are Determined
Roof fire ratings are not assigned to individual materials alone. It's really a roof assembly fire rating that includes:
- Roof covering (shingles, tile, metal, etc.)
- Underlayment
- Roof deck
- Insulation
- Fasteners and attachments
The entire roofing assembly must be tested as a whole to receive a fire classification. It provides assurance that there isn't one weak link that could compromise the whole thing.
Two primary standards are used in the United States:
- ASTM E108 – Standard Test Methods for Fire Tests of Roof Coverings
- UL 790 – Fire Tests of Roof Coverings
These standards are essentially equivalent and simulate real-world fire exposure.
Testing is conducted by certified laboratories, such as UL or Intertek, which issue official listings for compliant systems.
Key Fire Testing Components
There isn't a single test or measurement that's used to come up with a fire rating. Roof assemblies must pass several performance tests to determine a classification.
Spread of Flame Test
Measures how far flames travel across the roof surface.
- Class A Fire Rated: Maximum flame spread ~6 feet
- Class B Fire Rated: Maximum ~8 feet
- Class C Fire Rated: Maximum ~13 feet
- Insulation
- Fasteners and attachments
Burning Brand Test
Simulates burning debris, such as embers from a wildfire or adjacent structure, that could go beyond the roofing.
- Larger, heavier burning brands are used for higher classifications
- Tests whether the roof ignites or allows fire penetration
Intermittent Flame Test
This test exposes the roof to repeated bursts of flame to evaluate ignition resistance and durability.
Flying Brand Test
Instead of measuring how resistant a roof is to fire, this test evaluates whether the roof produces burning fragments that could spread fire to other structures.
Weathering and Rain Tests
Some systems undergo additional testing to ensure performance after exposure to moisture and the elements.
Measurement Criteria For Fire Ratings
The classification system for roofing is based on measurable performance metrics that are calculated during testing. Each test has established benchmarks that are used to clearly define the roof's fire rating.
Flame Spread Distance
One of the most important metrics is how far flames travel across the roof surface:
- Class A: ≤ 6 fee
- Class B: ≤ 8 feet
- Class C: ≤ 13 feet
Burning Brand Size and Weight
Each class must withstand a certain size of burning materials:
- Class A: Large, heavy burning brands (~12" x 12")
- Class B: Medium brands (~6" x 6")
- Class C: Small brands (~1.5" x 1.5")
Time to Ignition
Higher-rated systems resist ignition for longer periods under flame exposure.
Structural Integrity
During and after testing, the roof must:
- Not allow flames to penetrate to the roof deck
- Not produce flaming debris
- Maintain structural stability
- Prevent glowing embers from falling
Wind and Heat Conditions
Tests simulate real fire conditions, including:
- Wind speeds (~12 mph)
- High temperatures (up to ~1400°F for Class A/B)
How Roof Fire Ratings Apply in Texas
While Texas does not have statewide roof fire rating requirements beyond the adopted codes, the following factors can influence what rating is required:
Building Type and Occupancy
Commercial buildings, multi-family structures and high-occupancy facilities often require higher ratings compared to residential roofing.
Construction Type
Noncombustible buildings may have different requirements than wood-framed structures.
Proximity to Other Structures
Buildings located close together may require higher fire ratings to reduce fire spread risk.
Local Amendments
Cities and counties may adopt stricter standards than the base code.
Insurance Requirements
Insurance providers often favor or require Class A roofs for reduced risk.
Important Considerations About Roofing Fire Ratings
Fire Rating Applies to the Entire Roof Assembly
A key point is that fire ratings apply to the entire roofing system, not just the visible material. For example, metal roofing alone is noncombustible, but over a combustible deck, it may require testing to achieve a Class A rating.
Installation Matters
Incorrect roof installation or substitution of components can void a system’s fire rating.
Some Materials Are Pre-Classified
Certain materials (e.g., clay tile, slate, masonry) may be considered Class A without testing when installed over noncombustible decks.
Roof fire ratings in Texas are governed by a combination of conventional building codes, local enforcement and standardized testing procedures. The A, B, C classification system is based on how well a roofing assembly resists fire under controlled conditions.
Understanding how these ratings are determined and what they measure helps ensure that roofing systems are both code-compliant and provide ample protection when you're trying to choose a roofing material. If you have a property in the Austin, TX area and want professional guidance on roof fire ratings, give LOA a call or contact us online!
