Residential Building Inspector B1Public Safety and Special ConstructionMedium

A residential garage is being constructed with a floor that is required to be sloped to a drain. What is the minimum permissible slope for the garage floor?

  1. A1/2 inch per foot
  2. B1/8 inch per foot
  3. C1/4 inch per foot
  4. D1 inch per foot
Show answer & explanation

Correct answer: B. 1/8 inch per foot

Garage floors that are required to be sloped to a drain, such as those with a floor drain or where vehicles are parked, must have a minimum slope of 1/8 inch per foot (10.4 mm/m). This ensures proper drainage of liquids and prevents pooling.

Why the other options are wrong

  • A. This slope is excessive for a garage floor and not required.
  • C. This slope is common for shower pans or other wet areas, but not specifically the minimum for garage floors.
  • D. This slope is far too steep for a garage floor and not required.

Garage Floor Slope

The minimum gradient required for a garage floor to ensure proper drainage to a floor drain.

  • Applies to garage floors with drains
  • Minimum 1/8 inch per foot (10.4 mm/m)
  • Prevents water pooling

Memory trick: A garage slope, just an eighth, keeps water at bay.

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