North Carolina Building Contractor License Practice Exam

What classification of roof assemblies is most fire resistant?

1. Class B

2. Class C

3. Class A

4. 2 layers of felt

The correct answer is: 2 layers of felt

The classification of roof assemblies that is considered most fire resistant is represented by the two layers of felt. This type of roofing material provides a higher level of fire resistance due to the added layer, which can help in preventing the spread of fire and increasing the overall durability of the roof against heat. Roofing materials are usually classified based on their fire resistance according to standards set by organizations such as Underwriters Laboratories (UL). Class A roof assemblies typically include materials that have a high degree of fire resistance; however, when two layers of felt are employed, this configuration can exceed the standard Class A performance, particularly when installed properly and combined with other fire-resistant materials. In contrast, Class B and Class C roofs may still offer resistance to fire but do not perform as well under fire conditions as the two layers of felt would. They are designed to provide acceptable performance but may allow for a quicker spread of flames compared to the enhanced protections provided by the two layers of felt roofing. Thus, the answer representing the most fire-resistant option relates directly to the superior protective characteristics of the two layers of felt roofing system.