What does the 4:1 ladder rule mean?

• A. The ladder base should be one quarter of the ladder's working height away from the vertical surface; the ladder should extend at least 3 feet above the landing.
• B. The ladder base should be flush against the wall.
• C. The ladder base distance is equal to the ladder's working height.
• D. The ladder should extend above the landing by any amount.

Answer: (A)

Setting a ladder at the proper angle is essential for stability. The 4:1 rule means the base should be one quarter of the ladder’s working height away from the wall, and the ladder should extend at least 3 feet above the landing. This setup gives a safe, roughly 75-degree angle, which helps prevent tipping and slipping while you climb or descend and provides a sturdy handhold when transitioning to the landing.

Why this fits: the base distance being a quarter of the height ensures the ladder leans at a safe angle rather than being too vertical or too shallow. Requiring the ladder to extend at least 3 feet above the landing ensures you have something to grip and step onto for a safe transfer. The other options fail: placing the base flush against the wall is unstable; making the base distance equal to the full height creates too shallow an angle; extending above the landing by any amount doesn’t guarantee a safe, minimum handhold or transfer space.