Testing low-flame-spread wallcoverings on typical construction substrates in ASTM E84

Model building codes currently exempt wallcoverings less than 1/28 inch thick from any form of testing if their surface burning characteristics are no greater than paper wallcovering of the same thickness. However, the National Fire Protection Association's Life Safety Code Handbook points out that both the substrate and the air cavity behind the substrate may affect the performance of thin wallcoverings in fire conditions and recommends that wallcoverings less than 1/28 inch thick also be tested as they would be installed in the field. Model building code requirements regulate the surface burning characteristics of building materials by referencing, or basing their own standards on, ASTM E84. To determine whether ASTM E84 could be adapted to produce useable flame spread results when wallcoverings were tested on an actual wall assembly, 2 ASTM E84 tests were conducted on one low-flame-spread-rated wallcovering with an FSI (flame spread rating index) of 5 at the Underwriters Laboratories' facility in Northbrook, Illinois. Both tests used 5/8 inch Type X gypsum board as the construction substrate on full wall assemblies. Results indicated that the wallcovering performed differently when tested as a wall assembly. (Abstract quotes from original text)