What is the minimum weight of moisture-proof felt?

What is the minimum weight of moisture-proof felt?

• A. 15 lb/100 sq ft
• B. 12 lb/100 sq ft
• C. 20 lb/100 sq ft
• D. 10 lb/100 sq ft

Answer: (A)

Minimum weight for moisture-proof felt is 15 lb per 100 square feet. In roofing underlayment, the felt’s weight reflects its thickness and tear resistance, which are crucial for providing a reliable moisture barrier under the roofing material. A 15-lb/100-sq-ft felt offers enough strength to resist tearing during installation and to help prevent moisture intrusion, while still being practical to handle and install. Lighter options, like 10 or 12 lb, would be more prone to tearing and moisture leaks, making them less protective. A heavier option, such as 20 lb, does meet performance needs, but it’s not the minimum requirement. Therefore, 15 lb per 100 sq ft is the accepted minimum.

Minimum weight for moisture-proof felt is 15 lb per 100 square feet. In roofing underlayment, the felt’s weight reflects its thickness and tear resistance, which are crucial for providing a reliable moisture barrier under the roofing material. A 15-lb/100-sq-ft felt offers enough strength to resist tearing during installation and to help prevent moisture intrusion, while still being practical to handle and install. Lighter options, like 10 or 12 lb, would be more prone to tearing and moisture leaks, making them less protective. A heavier option, such as 20 lb, does meet performance needs, but it’s not the minimum requirement. Therefore, 15 lb per 100 sq ft is the accepted minimum.