CSLB General Building (B)SafetyMedium
A contractor is using a scaffold that is 15 feet high. The scaffold platform is 3 feet wide. What is the minimum base dimension for this scaffold to ensure stability, assuming a 4:1 height-to-base ratio is required by Cal/OSHA?
- A5.0 feet
- B3.75 feet
- C4.0 feet
- D3.0 feet
Show answer & explanationAnswer & explanation
Correct answer: B. 3.75 feet
Cal/OSHA requires that the height of a scaffold not exceed four times its minimum base dimension unless it is tied off or guyed. For a 15-foot high scaffold, the minimum base dimension must be 15 feet / 4 = 3.75 feet.
Why the other options are wrong
- A. This would be the minimum base for a 20-foot high scaffold.
- C. This would be the minimum base for a 16-foot high scaffold.
- D. This is the platform width, not the calculated minimum base dimension for stability.
Scaffold Height-to-Base Ratio
Cal/OSHA mandates that the height of a scaffold must not exceed four times its minimum base dimension unless it is tied off, guyed, or braced.
- Ratio is 4:1 (height:base).
- Applies to freestanding scaffolds.
- Tying off or guying allows greater heights.
Memory trick: Scaffold height is 'Four-Times-Base' for stability.