Max height of ladder jack scaffold?

• A. 16'
• B. 12'
• C. 18'
• D. 20'

Answer: (A)

Ladder jack scaffolds are a simple setup that uses two ladders as the uprights with a plank resting on ladder jacks. The height you can safely work from is limited to keep the base stable and the platform within the ladders’ supported range. As you raise the scaffold higher, the risk of tipping, ladder movement, and plank deflection increases, and the access point for climbing onto the platform becomes less secure. To maintain a safe balance of stability, load distribution, and accessible footing, the practical and widely accepted limit for this type of scaffold is 16 feet above the ground.

Choosing a taller height would push beyond the safe operating range of ladder jack systems, where the joints and support points can’t reliably handle the forces, so for higher work you’d switch to a different scaffold type. Heights like 12 feet are below the maximum, while 18 and 20 feet exceed the safe limit for ladder jack scaffolds.