What is the minimum height of a ladder safely used against a building?

The minimum height of a ladder safely used against a building is commonly recommended to be at least 16 feet. This height ensures that the ladder extends beyond the apex of the structure, allowing for safe climbing and dismounting. Ladders shorter than this can put workers at risk since they might not reach over the edge of the roof, which can lead to dangerous situations when attempting to access the roof or perform work duties.

In the context of regulations and safety standards, using a taller ladder provides a better angle for stability while also minimizing the likelihood of falls. Additionally, various safety organizations often recommend that a ladder should extend at least 3 feet above the landing point to provide adequate handhold when climbing on or off. Therefore, the height of 16 feet is an appropriate minimum to ensure that these safety considerations are met effectively.