1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULUNDERWRITERS LABORATORIES INC. CERTIFICATION REQUIREMENT DECISIONThis Certification Requirement Decision is prepared and published by Underwriters Laboratories Inc.(UL). It is normative for the a
2、pplicable UL Product Certification Program(s); however, it is currently notpart of the UL Standard(s) referenced below.Product Category (CCN): TFWX, TFXX, TGFUStandard Number: UL 790Standard Title: Standard Test Methods for Fire Tests of Roof CoveringsEdition Date: April 22, 2004Edition Number: 8Sec
3、tion / Paragraph Reference: 4.4.1Subject: Preparation / Application of Test SamplesDECISION:4.4.1 The prepared roof covering material to be tested is to be applied, in accordance with the testsponsors instructions, to the applicable number of test decks as specified in Table 3.1. The material is toe
4、xtend to, and be flush with, the edges of the deck on the sides and top. At the leading edge, the materialis to be positioned except for a 1 inch (25.4 mm) overhang at the leading edge, such that there is minimumcoverage, or a minimum number of layers, over the horizontal deck joints. For mechanical
5、ly attached andfully adhered single-ply membrane roof covering systems it is not prohibited to pull the membrane tautover the edges of the assembly to fit snugly against the deck and secure it to the wood supports of thetest deck. The use of a 1-in (25-mm) width metal batten strip or wire fastened o
6、n top of and along eachside edge is not prohibited for mechanically attached single-ply membrane roof covering systems.RATIONALE FOR DECISION:The intent of Section 4.4.1 on Preparation and Application of the samples in UL 790 is to examineproducts in such a manner that there is minimum coverage, or
7、a minimum number of layers, over thehorizontal deck joints. The lay-out of three-tab shingles most prevalent when the language was developed,with a 1 inch overhang at the leading edge, would result in the horizontal joint occurring directly betweentwo head laps of the shingle. However, when testing
8、certain products available in the marketplace today,with a 1 inch overhang at the leading edge, many of these products would result in maximum coverageover the horizontal deck joints.In order to maintain consistency with the intent of the Standard UL 790, and in accordance with ULslong-standing prac
9、tice, this Certification Requirement Decision clarifies that the roof covering material isto be positioned such that there is minimum coverage, or a minimum number of layers, over the horizontaldeck joints.Copyright 2013 Underwriters Laboratories Inc.UL, in performing its functions in accordance wit
10、h its objectives, does not guarantee or warrant thecorrectness of Certification Requirement Decisions it may issue or that they will be recognized or adoptedby anyone. Certification Requirement Decisions are the opinion of Underwriters Laboratories Inc. inpractically applying the requirements of the
11、 standard. They do not represent formal interpretations of thestandard under American National Standards Institute (ANSI) processes. UL shall not be responsible toanyone for the use of or reliance upon Certification Requirement Decisions by anyone. UL shall not incurany obligation or liability for d
12、amages, including consequential damages, arising out of or in connectionwith the use or reliance upon Certification Requirement Decisions. The electronic version of theCertification Requirement Decision is the current version and previously printed copies may be outdated.UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULThis document is published as a service to ULs certification customersSTANDARD NUMBER: UL 790 -2-
