The '1 in 4' rule (also known as the '4 to 1' rule) is a simple piece of guidance that you should always follow when you use a leaning ladder.
If you've ever wondered what angle to aim for when setting a ladder against a vertical wall, here's the rule:
For every 4 feet of height, position the base of the ladder 1 foot away from the wall.
In other words, the distance between the wall and the base of your ladder should be one quarter of the ladder's height (putting the ladder at a 75° angle). This applies whether you're measuring in feet or metres.
This angle improves the ladder's stability and reduces its risk of slipping. The Health & Safety Executive's ladder safety guidelines state that you should always follow the '1 in 4' rule when setting up a ladder.
READ MORE: How to Stop Ladders Slipping
An example of the '1 in 4' rule in action
Let's say you're setting up an extension ladder.
If the ladder meets the wall at a point that's exactly 4 metres off the ground, the foot of the ladder should be positioned precisely 1 metre away from the wall.
If the ladder reaches 8 metres off the ground, place the bottom of the ladder 2 metres back from the wall.
Of course, the numbers are unlikely to be quite that neat in real life, so you may have to get your calculator out! Just make sure the distance between the wall and the base of the ladder = the distance between the top of the ladder and the ground divided by 4.
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SEE ALSO: Can step ladders be leaned against a wall?