Ladders make working at great heights possible. A stepladder must be tall enough to bring a worker's hands to the height of the work. Extension ladders also have to be long enough to set at the correct pitch depending on the heights they will be used to reach. Choose a ladder that will safely put you at the correct height for the work at hand.
Determine the height of the work to be done. Use a measuring tape to get an exact measurement of the height.
Choose the right type of ladder depending on the height of the work. A stepladder is better suited to any work up to a height of 10 feet. Extension ladders are available for work from 10 feet to over 50 feet high.
Calculate stepladder length based on work height. A step ladder must reach within four feet of the work surface for a user of average height. A six-foot step ladder is needed for work on a 10-foot ceiling.
Calculate the length for extension ladders based on work heights and pitch angles. Extension ladders are correctly pitched when the base is one quarter its height from the wall. The base of a 24-foot ladder stands 6 feet away from the wall. An extension ladder should extend one foot beyond the work surface of a wall up to 34 feet. Add another foot to accommodate the pitch at 34 feet and an additional foot at each three foot interval to follow. Extend the top of an extension ladder three feet above a roof eave when accessing a rooftop.