By Gregory Havel
最近对网站和印刷广告的几个“大盒子”家庭改善商店的审查显示，屋顶材料促进为“A级和B级防火”。这种广告是不准确的，可以导致屋顶materials在错误的应用程序中安装的错误类型。
Underwriters Laboratories（UL）790和美国测试和材料协会（ASTM）E108使用相同的测试方法和程序来测试反抗of roof coverings to fire sources outside the building on which the roof coverings are installed. These tests apply to roof coverings on either combustible or noncombustible decks when the roof coverings are installed as designed. These tests are the ones most frequently referenced in building and fire codes in North America.
Roof如果屋顶覆盖物不符合任何其他类别的要求，则覆盖物被归类为A类A，B类，C类或“未定寸”。
A级是最佳评级，提供最大的抵抗力，“未命出”提供对火最少的抵抗力。A级屋顶覆盖物包括板岩，混凝土或粘土瓷砖;玻璃纤维沥青成分带状疱疹;和一些金属屋顶。未经治疗wood摇晃和带状疱疹往往是“无关”，尽管用阻燃化学品浸渍可以给予他们B级防火。包括屋顶组件中的额外防火材料可以给予它级别的额定值。
UL 790和ASTM E108通过评估以下内容来分类屋顶的性能：
- 通过屋顶覆盖和甲板的火焰渗透到阁楼空间。
- Flame spread on the surface of the roof covering.
- 屋顶覆盖为产生余烬的可能性。
A类屋顶覆盖物可防止严重的火灾测试曝光; they provide good protection to the roof deck, do not slip from position, and are unlikely to produce flying brands.
B级车顶覆盖物可防止温和的防火试验曝光;他们提供中度保护to the roof deck, do not slip from position, and are unlikely to produce flying brands.
C类屋顶覆盖物可防止光消防试验曝光;它们为屋顶甲板提供了较小程度的保护，不要从位滑落，不太可能产生飞行品牌。
“未犹豫的”屋顶覆盖物是那些尚未测试的屋顶覆盖物或者甚至是C类评级的测试失败。
这些测试证明了表现of roof coverings during the types and duration of fire exposures involved in the testing. They are not intended to prove that the roof coverings will be undamaged during the tests since even a Class A roofing material can be damaged by fire. They are not intended to compare the expected performance of the roof coverings under all types of actual fire conditions.
The most common type of fire source outside a building is the “flying brand.” The brand in photo 1 was generated during the burn-down阶段根据国家消防协会1403，获取结构中的火灾训练，Standard on Live Fire Training Evolutions,并降落在距离燃烧建筑约50码的沥青路面上。它从左下到右下方测量了三英寸（7.65厘米），从左下到左上5英寸（12.7厘米），厚约1英（3.15厘米）英寸。
(1)
Photo 2 shows the comparative sizes of the brands used in testing roofing materials before ignition.
(2)
- 班级品牌措施12 x 12 x 2英寸（30.5 x 30.5 x 5.7厘米），重量为4.4磅（2,000克），由三层12层12个木条制成彼此垂直于彼此装配在一起。
- Class B brands measure 6 x 6 x 2¼ inches (15.25 x 15.25 x 5.7 cm), weigh 1.1 pounds (500 grams), and are made of three layers of six wood strips stapled together perpendicular to one another.
- Class C brands measure 1.5 x 1.5 x 0.781 inches (38 x 38 x 19.8 mm), weigh 3.26 ounces (9.25 grams), and are made of solid wood with saw kerfs in opposite faces cut perpendicular to each other.
A类和B类品牌的规模大于野火常用的尺寸。
对于测试，测试品牌放置在屋顶覆盖物的表面上，该覆盖物将在可燃或非可燃的屋顶甲板上进行测试，如其设计所确定的，底部的底部边缘（30.5厘米）的底部边缘of the roof’s slope. A ducted fan is set up blowing air upslope at a speed of 12 mph (19.2 km/h). The burning brand sample is monitored, photographed, and videoed for up to 1.5 hours, until the brand burns out, or until the roof assembly fails.
The distance that the fire spreads on the roof covering from the edges of the brand is also measured and recorded. Class B and C roof coverings are permitted larger flame spread distances than Class A.
覆盖在可燃屋顶甲板上的屋顶的失效是屋顶甲板点燃的点。在非洲屋顶甲板上覆盖的屋顶的失效是火灾渗透到屋顶甲板上的点。任何类型的甲板上的屋顶覆盖的故障也可能由火焰传播在屋顶覆盖上，这对于被测试的分类来说太大。
可燃屋顶甲板上的屋顶覆盖物可能需要测试三次，因为可燃结构材料添加不存在的屋顶结构上不存在的变量。
Roof coverings have no labels on individual shingles or shakes. The only indication of the fire test classification of the roof covering is the label on the bundle (photo 3) or roll. Similar information may be included on the invoice from the building materials supplier. Building owners should be encouraged to keep copies of these documents for future reference by building officials and insurance agents.
(3)
Code enforcement officials should work toward a requirement for at least Class B (and preferably Class A) roofing materials in neighborhoods where buildings are close together and are prone to fire spread by brands as well as in areas where wildfires are a threat. In some areas of North America, this has already been accomplished; in other areas, it is still a work in progress.
消防员必须记住，屋顶的一级比屋顶甲板和支持它的椽子或桁架更强大;屋顶的课程在阁楼的火灾中没有意义。这些屋顶分类是从屋顶外部接触火灾的评级系统。它们不反映其对建筑物内部的火灾的抵抗力或其结构强度的垂直通风。
作者谨此感谢消防员安全研究所和UL所长的Stephen Kerber P.E.他对本文的研究援助。
将本文下载为PDF这里
格雷戈里哈维尔is a member of the Town of Burlington (WI) Fire Department; retired deputy chief and training officer; and a 35-year veteran of the fire service. He is a Wisconsin-certified fire instructor II, fire officer II, and fire inspector; an adjunct instructor in fire service programs at Gateway Technical College; and safety director for Scherrer Construction Co., Inc. Havel has a bachelor’s degree from St. Norbert College; has more than 35 years of experience in facilities management and building construction; and has presented classes at FDIC.
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