NRCA states that when the roof slope is greater than 2:12, plies should be laid parallel to the slope. What is this technique called?

NRCA states that when the roof slope is greater than 2:12, plies should be laid parallel to the slope. What is this technique called?

• A. Strapping the plies
• B. Laying the plies parallel
• C. Plies parallel method
• D. Slope-aligned installation

Answer: (A)

On roofs steeper than 2:12, placing the plies so they run along the slope direction helps control how the material behaves under wind, gravity, and drainage, and it keeps the joints aligned for a secure, watertight bond across long runs. This approach is called strapping the plies, a term used to describe using strapping or similar means to hold each ply in place as it’s installed along the slope. The orientation matters because when plies run parallel to the slope, overlaps and seams tend to shed water more effectively and resist wind uplift on steep surfaces. The other options are descriptive phrases rather than established terms, so the standard name NRCA uses for this technique is strapping the plies.

On roofs steeper than 2:12, placing the plies so they run along the slope direction helps control how the material behaves under wind, gravity, and drainage, and it keeps the joints aligned for a secure, watertight bond across long runs. This approach is called strapping the plies, a term used to describe using strapping or similar means to hold each ply in place as it’s installed along the slope. The orientation matters because when plies run parallel to the slope, overlaps and seams tend to shed water more effectively and resist wind uplift on steep surfaces. The other options are descriptive phrases rather than established terms, so the standard name NRCA uses for this technique is strapping the plies.