A standard step ladder stands on its own when fully opened and locked; an extension ladder needs a suitable support and a non-self-supporting setup. OSHA requires a locking device on stepladders and sets an approximately 4-to-1 placement ratio for non-self-supporting ladders. Choose by the access point and work position, then follow the exact ladder instructions.
The useful distinction is support. A standard step ladder is self-supporting when opened and locked. An extension ladder leans against a suitable support and adjusts in length, so its placement and landing access need a different plan.
Compare the work position
| Factor | Step ladder | Extension ladder |
|---|---|---|
| Support | Stands open on its feet | Leans against a suitable support |
| Best fit | A work area where no wall or landing support is available | Reaching a fixed upper level or work point with a suitable support |
| Setup check | Open fully and lock the spreaders or locking device | Set the base and top support as directed for a non-self-supporting ladder |
| Key limit | Do not use the top or top step as a step | Do not use it horizontally as a work platform |
OSHA requires a metal spreader or locking device to hold a stepladder open. Werner also distinguishes standard step ladders from specific models designed for leaning, so use a leaning configuration only when the manufacturer’s label permits it.
Set up the extension ladder for its access point
OSHA’s construction standard places a non-self-supporting ladder so the horizontal distance from its foot to the top support is about one-quarter of its working length. When a portable ladder accesses an upper landing, its side rails must extend at least 3 feet above that landing. If its length makes that extension impossible, OSHA specifies securing the top to a rigid support and providing a grasping device.
Use ladders on stable, level surfaces unless they are secured against displacement, stay within their rated load and keep the worker’s body inside the side rails. For the load and duty-rating decision, see ladder duty ratings. Review hard-hat types and classes and safety boot labels for other jobsite PPE decisions. Browse ladders and scaffolding.
Sources: OSHA construction ladder requirements, OSHA’s extension-ladder safety fact sheet, and Werner’s guidance on using step ladders in a leaning position.
Common questions
Can I lean a standard step ladder against a wall?
No. Werner says standard step ladders are designed for use fully open with their spreaders locked. Use a leaning configuration only when the ladder is specifically designed and labeled for it.
How do I set an extension ladder angle?
For construction use, OSHA says a non-self-supporting ladder's base should be about one-quarter of its working length from the top support, the common 4-to-1 placement ratio. Follow the ladder instructions and site safety plan.
Which ladder should I use to reach a roof landing?
An extension ladder is the usual choice when the work area provides a suitable support. OSHA requires its side rails to extend at least 3 feet above an upper landing, or requires a secured top and grasping device when the ladder length makes that impossible.
Can I stand on the top step of a step ladder?
No. OSHA says the top or top step of a stepladder shall not be used as a step. Follow the maker's maximum standing-level instructions as well.