Illinois Roofing Practice Exam

The recommendation made by the National Roofing Contractors Association (NRCA) for using a weatherproof membrane under slate roofing is primarily based on the prevention of water infiltration and ensuring the longevity of the roofing system. When the slope of a roof is greater than 4:12, the likelihood of water pooling and the potential for leaks is significantly reduced. Slate roofing, while durable, requires proper installation techniques to prevent moisture issues. By utilizing a weatherproof membrane in these circumstances, the roofing system gains an added layer of protection against water intrusion, particularly in areas prone to heavy rainfall or snow.

The other options do not align with the NRCA’s guidance. A slope of less than 4:12 is more vulnerable to water retention, increasing the risk of leaks, while including a requirement for flat roofs or any specific slope above 6:12 without addressing the broad recommendation for slopes greater than 4:12 deviates from best practices established in roofing guidelines. This highlights the NRCA's focus on safeguarding structures by implementing effective moisture control measures appropriate for various roof slopes.