1 Scope

1.1 These requirements cover the measurement of the relative fire characteristics of roof coverings exposed to simulated fire sources originating from outside a building on which the coverings are installed. They are applicable to roof coverings intended for installation on either combustible or noncombustible roof decks (see 4) when the roof coverings are applied as intended. The following test methods are included:

1. a) Intermittent-Flame Exposure test;

2. b) Spread of Flame test;

3. c) Burning Brand test;

4. d) Flying Brand test; and

5. e) Rain test.

1.2 Three classes of fire exposure are described.

1. a) Class A roof coverings that are expected to be effective against severe fire exposures. Under such exposures, roof coverings of this class afford a high degree of fire protection to the roof deck, do not slip from position, and are not expected to produce flying brand.

2. b) Class B roof coverings that are expected to be effective against moderate fire exposures. Under such exposures, roof coverings of this class afford a moderate degree of fire protection to the roof deck, do not slip from position, and are not expected to produce flying brand.

3. c) Class C roof coverings that are expected to be effective against light fire exposures. Under such exposures, roof coverings of this class afford a light degree of fire protection to the roof deck, do not slip from position, and are not expected to produce flying brand.

Summary of Topics

This new edition of ANSI/UL 790 dated February 18, 2022 includes the following changes in requirements:

– Listing of Test Methods in Scope; 1.1

– Update of Scope and Roof Deck Clarification; 1.2, 1.4

– Class B Burning Brand Test Modifications; Table 3.1, 8.4.2.1

– Figure 4.1 Title Change and Editorial Corrections; 4.2.1, 4.2.2

– Roof Coverings Clarification; 4.2.3, 4.2.4

– Burning Brand Deck Clarification; 4.2.5

– Spread-of-Flame Test Deck Clarification; 4.3.1

– Clarification to 4.4.1

– Thermocouple Stabilization for Calibration; 5.5

– Intermittent-Flame Test Air Supply; 6.1

– Ignition of Brands Timing; 8.3.1

– Flying-Brand Test Air Current Clarity; 9.3