For maximum stability, extension ladders should be pitched at a 75.5 degree angle. One way to check the angle is to stand with your toes against the bottom of the ladder and your arms extended straight out. If you can grasp a rung at shoulder height, you’re in the ballpark.

Another way to determine the angle is to use the Ladder Safety app from the National Institute for Occupational Safety and Health (NIOSH). Just hold your mobile device against a side rail and the app displays the angle while using visual and audio cues to guide you. A red indicator tells you the ladder pitch is too steep or shallow; a green...

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