Which statement describes the slope criterion for low slope roofing?

• A. 4:12 or less.
• B. 2:12 or less.
• C. 3:12 or less.
• D. 6:12 or less.

Answer: (B)

The key idea is where low-slope roofing ends and steep-slope roofing begins. In practice, low-slope roofing is defined as slopes of 2:12 or less, meaning for every 12 inches of horizontal run the roof rises no more than 2 inches. This threshold is used because membrane and built-up systems are designed to shed water effectively at gentle pitches and rely on particular flashing and seam details that suit shallow slopes. When the slope exceeds 2:12, different roofing methods, materials, and flashing requirements come into play, so the boundary is set at 2:12 or less. That’s why the statement describing 2:12 or less is the correct choice. The other options describe steeper slopes and don’t align with the standard low-slope criterion.