Ladders are useful in any number of situations – from simple lightbulb changes to complex projects like rooftop rebuilds.
While a ladder will help you do your job, it will also expose you to risk. Any time you climb a ladder, you're working at height. And when you're working at height, you're at risk of a fall.
Climbing ten feet up a ladder might not seem terribly intimidating. But what if the ladder you had to climb was straight up the side of a multi-story office building? Even if you're not afraid of heights, that's still a daunting climb.
(Learn more in Fall Protection and Ladders)
This is where cages can help.
In an effort to prevent falls from these fixed ladders, cages or basket guards enclose the ladder’s climbing space and are attached to the building or the ladder itself. These cages can help w
orkers regain their balance or reaffirm their foothold when their climb doesn't go smoothly, instead of slipping off a rung and falling backward off the ladder. In some cases, the cage can even offer an opportunity for rest or to readjust your gear during a climb.
OSHA requires that all fixed ladders taller than 20 feet must have a cage that extends to 42 inches over the top of the landing and begins at least seven feet from the bottom to avoid workers bumping their heads. As with any rule, there are some exceptions to this one. Certain structures, like silos, can substitute alternate safety devices that are more functional for the situation. If you encounter a cageless ladder that you suspect isn't in compliance, consult the relevant standards to determine whether it constitutes a safety violation.
But the simple answer to your question is 20 feet. In most cases, any ladder taller than that must be equipped with a cage to ensure a safer climb or descent.