A waterproof deck surface is 14 feet deep and must slope 1/4 inch per foot to the drain. What vertical fall is needed?
Correct Answer
D) 3 1/2 inches.
A quarter inch per foot over 14 feet equals 3.5 inches of fall.
Why This Is the Correct Answer
A quarter inch per foot over 14 feet equals 3.5 inches of fall.
Why the Other Options Are Wrong
Option A: 1 3/4 inches.
1 3/4 inches. is below the supported result for waterproofing slope calculation; it likely omits allowance, conversion, coverage, or final round-up.
Option B: 2 inches.
2 inches. is below the supported result for waterproofing slope calculation; it likely omits allowance, conversion, coverage, or final round-up.
Option C: 2 1/2 inches.
2 1/2 inches. is below the supported result for waterproofing slope calculation; it likely omits allowance, conversion, coverage, or final round-up.
Memory Technique
Checking Balcony takeoff: count the condition before counting the package.
Reference Hint
Study anchor (closed-book): memorize Waterproofing slope calculation from 2025 California Building Code, California Code of Regulations Title 24 / Title 24 California Building Code exterior walking surface drainage; know the rule or calculation trigger without relying on exam-room lookup.
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