Illinois Roofing Practice Exam

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Prepare for the Illinois Roofing Exam with comprehensive quizzes. Utilize flashcards and multiple-choice questions, each with detailed hints and explanations. Start your journey to becoming a certified roofing professional in Illinois today!

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A flat roof that measures 40 feet by 20 feet would have a net roof area of 800 square feet or 8 squares. If that same building had a gable roof with a 6:12 slope, what would be the net roof area?

8.94 Squares
6.42 Squares
7.25 Squares
9.18 Squares

The correct answer is: 8.94 Squares

To determine the net roof area of a gable roof, it is essential to understand how the slope affects the roof's dimensions. For a flat roof measuring 40 feet by 20 feet, the total area calculates to 800 square feet, which translates to 8 squares (since 1 square is equal to 100 square feet). For a gable roof with a slope of 6:12, you need to factor in the rise, which affects the overall footprint of the roof. In this case, the rise is measured as half the width of the roof run. The total span of the gable roof will be the width of the building multiplied by the slope factor. Calculating the roof's length remains constant at 40 feet. The roof's width significantly changes due to the slope. The rise can be calculated by using the ratio: for every 12 horizontal units, there are 6 vertical units. Therefore, if you consider 20 feet (the width of the building), it will yield a rise of 5 feet (20 feet run ÷ 12 = 1.67, then 1.67 x 6). By using the Pythagorean theorem, we find the length of the slope from the