SafetyQuestion 653 of 700
CALCULATION: A free-standing supported scaffold has a minimum base width of 5 feet. Using the common 4:1 height-to-base ratio, at what height must the scaffold first be tied, guyed, or braced to the structure to prevent tipping?
a.10 feet
b.20 feet
c.25 feet
d.40 feet
Explanation
Correct: the maximum unrestrained height is 4 times the least base dimension, so 4 x 5 ft = 20 ft; above 20 ft the scaffold must be tied or braced to the structure. 10 ft understates it (that would be a 2:1 ratio); 25 ft and 40 ft exceed the 4:1 limit for a 5-ft base and would allow an unstable, tip-prone scaffold.
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