OSHA 10-Hour Construction ReviewStairways and LaddersMedium
A worker is using a portable ladder that is placed against a wall. To ensure proper stability, what is the recommended angle for placing the ladder, often referred to as the 4 to 1 rule?
- AThe base of the ladder should be 1 foot away from the wall for every 6 feet of working length.
- BThe base of the ladder should be 1 foot away from the wall for every 3 feet of working length.
- CThe base of the ladder should be 1 foot away from the wall for every 5 feet of working length.
- DThe base of the ladder should be 1 foot away from the wall for every 4 feet of working length.
Show answer & explanationAnswer & explanation
Correct answer: D. The base of the ladder should be 1 foot away from the wall for every 4 feet of working length.
The 4 to 1 rule states that for every 4 feet of vertical height the ladder reaches, its base should be 1 foot away from the wall. This creates an approximate 75-degree angle, which is considered the safest and most stable angle for a portable ladder.
Why the other options are wrong
- A. This ratio would result in a ladder angle that is far too shallow and highly unstable.
- B. This ratio would result in a ladder angle that is too steep and less stable.
- C. This ratio would result in a ladder angle that is too shallow and prone to sliding out.
4 to 1 Ladder Rule
For every 4 feet of vertical height a ladder reaches, its base should be 1 foot away from the supporting surface.
- Establishes a safe 75-degree angle.
- Prevents tipping backward or sliding out.
- Crucial for portable ladder stability.
Memory trick: Four up, one out, no doubt!