A roof drain is 44 ft from a high point, and tapered insulation is set at 1/4 in. per foot. What elevation drop should the cricket provide?
Correct Answer
A) 11 in.
At 1/4 in. per foot over 44 ft, the drop is 44 x 0.25 = 11 in. Other choices use shorter runs or round to a convenient foot.
Why This Is the Correct Answer
At 1/4 in. per foot over 44 ft, the drop is 44 x 0.25 = 11 in. Other choices use shorter runs or round to a convenient foot.
Why the Other Options Are Wrong
Option B: 9 in.
roof drain slope, choice a: 9 in. backs into 36 when divided by 1/4; the accepted setup gives 44 on that same base.
Option C: 10 in.
roof drain slope, choice b: 10 in. backs into 40 when divided by 1/4; the accepted setup gives 44 on that same base.
Option D: 12 in.
roof drain slope, choice d: 12 in. backs into 48 when divided by 1/4; the accepted setup gives 44 on that same base.
Memory Technique
Store roof drain slope with its last math move; nearby answers are usually unfinished versions of 11 in.
Reference Hint
Open Roofing Construction and Estimating, Atcheson, 1995/2022 reprint; use the index entry or section for "Roof taper slope to drain calculation" to confirm that At 1/4 in.
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