The range 210 mm to 235 mm is the minimum size for which element?

The range 210 mm to 235 mm is the minimum size for which element?

• A. Stair tread including nosing
• B. Crawl space opening
• C. Header width
• D. Door height

Answer: (A)

The range 210 mm to 235 mm is the minimum size for stair tread depth including the nosing. This measurement ensures there is enough surface for a foot to land securely on each step, even with the extra projection of the nosing. It accounts for safe footing and consistent step feel from one tread to the next. Other elements—crawl space openings, header widths, or door heights—are governed by different dimensions and aren’t specified by this tread depth range, so they wouldn’t use this measurement.

The range 210 mm to 235 mm is the minimum size for stair tread depth including the nosing. This measurement ensures there is enough surface for a foot to land securely on each step, even with the extra projection of the nosing. It accounts for safe footing and consistent step feel from one tread to the next. Other elements—crawl space openings, header widths, or door heights—are governed by different dimensions and aren’t specified by this tread depth range, so they wouldn’t use this measurement.