Extension above the landing: 3 ft
29 CFR 1926.1053(b)(1): a portable ladder used to reach an upper landing must have side rails that extend at least 3 ft (0.9 m) above the upper landing surface.
Trap: 4 ft comes from confusing the extension with the 4:1 setup ratio, which is about base setback, not extension.
When the ladder is too short
If the 3 ft extension is not possible, 1926.1053(b)(1) requires both:
- secure the ladder at its top to a rigid support that will not deflect, and
- provide a grasping device, such as a grabrail.
OSHA's 2004 interpretation confirms the ladder must be secured in addition to the grasping device. A grabrail alone does not comply, and securing the top alone does not comply. Steepening past 4:1 is not an alternative.
The 4:1 setup rule
1926.1053(b)(5)(i): for a non-self-supporting ladder, the horizontal distance from the top support to the foot is about one-quarter of the working length.
Working length is measured along the ladder, from the foot to the top support.
- 20 ft working length: 20 ÷ 4 = 5 ft setback.
- 16 ft working length: 16 ÷ 4 = 4 ft setback.
Traps:
- Measuring vertical height from the ground is the common error; measure along the ladder.
- Do not measure to the top of the side rails. The extension above the landing is not part of working length; the rule stops at the top support.
- One-eighth (20 ÷ 8 = 2.5 ft) applies only to job-made wood ladders whose side rails continue past the top cleat.
Load capacity: 4 times, Type 1A 3.3 times
1926.1053(a)(1): each portable ladder must support at least 4 times its maximum intended load. For 300 lb: 4 × 300 = 1,200 lb.
Traps:
- 3.3x (3.3 × 300 = 990 lb) applies only to extra-heavy-duty Type 1A metal or plastic ladders.
- 6x (1,800 lb) is the scaffold suspension rope factor.
- 2x (600 lb) is not the ladder rule.