What is the minimum overlap for vertical joints of felt or paper used as a weather resistant barrier on exterior walls?

• A. Not less than 6
• B. Not less than 4
• C. Not less than 8
• D. Not less than 12

Answer: (A)

The minimum overlap for vertical joints of felt or paper used as a weather-resistant barrier on exterior walls is typically stated as not less than 6 inches. This standard ensures that there is adequate waterproofing and that water, if it manages to penetrate the outer cladding, will not easily reach the structural elements of the wall.

The purpose of this overlap is to create a continuous barrier that prevents moisture from entering the wall assembly, which can lead to mold growth, rot, and other forms of deterioration. A 6-inch overlap is generally considered sufficient to allow for proper drainage and to reduce the likelihood of any water bypassing the barrier.

By adhering to this standard, builders ensure that structures remain better protected against the elements, which contributes to long-term durability and integrity of the building.