Illinois Roofing Practice Exam

The correct width of ice dam protection for a roof with a slope of 6:12 and eaves extending 30 horizontal inches is typically calculated based on the recommended guidelines for ice dam protection, which often stipulate that the protection should extend at least 24 inches inside the warm wall of the building.

In this scenario, since the roof pitch is 6:12 (which means for every 12 inches of horizontal run, the roof rises 6 inches), it is important to provide adequate protection against ice dams that can occur at the eaves during winter months. The usual recommendation is to extend the ice dam protection a minimum of 24 inches beyond the interior wall line, but in this specific question, considering the total width needed to account for the overhang and the recommended practice, the total safety measure is to extend protection further, hence 48 inches is indicated.

This total of 48 horizontal inches encompasses the 30 inches of eave extension plus an additional 18 inches to address the ice dam potential effectively, which aligns with best practices in roofing design in areas prone to significant snowfall. Therefore, this answer aligns with standard practices established for ice dam protection.