OSHA 10-Hour Construction ReviewStairways and LaddersEasy
A worker is using a portable ladder that is placed against a wall. To ensure proper stability and prevent slipping, what is the correct horizontal-to-vertical ratio for setting up a portable ladder?
- A1:4 (1 foot out for every 4 feet up)
- B1:5 (1 foot out for every 5 feet up)
- C1:3 (1 foot out for every 3 feet up)
- D1:2 (1 foot out for every 2 feet up)
Show answer & explanationAnswer & explanation
Correct answer: A. 1:4 (1 foot out for every 4 feet up)
OSHA mandates the 4 to 1 rule for portable ladders: for every 4 feet of vertical height the ladder reaches, its base should be placed 1 foot horizontally away from the wall or upper support. This ratio provides optimal stability.
Why the other options are wrong
- B. This ratio places the ladder too far out, making it unstable and increasing the risk of the ladder tipping backward.
- C. While better than 1:2, this is still steeper than recommended for optimal stability.
- D. This ratio is too steep and increases the risk of the ladder sliding out.
4 to 1 Ladder Rule
For every 4 feet of vertical height a portable ladder reaches, its base should be 1 foot horizontally away from the supporting structure.
- Applies to portable ladders.
- Ensures optimal stability.
- Prevents slipping or tipping.
Memory trick: Four up, one out, no doubt!