Sheet 24Mix-up sheet · Falls, ladders and scaffolds
Ladder rules on the STSC: 4-to-1, 3 feet and the top step
The 4-to-1 rule sets the angle of a leaning ladder: for every 4 feet of working length, the feet go 1 foot out from the point where the top rests, which stands the ladder at roughly 75 degrees. 29 CFR 1926.1053 surrounds it with three numbers that are easy to swap for one another: 3 feet above a landing, a 19-inch break in elevation, and a stepladder top that is never a step.
Crews say 4-to-1, 1-in-4 or 1:4, and all three describe the same setup. The 4 is measured along the rails, from the feet to the top support. The 1 is the horizontal distance from that support back to the feet. Measuring 4 straight up the wall instead gives nearly the same base on an ordinary setup, which is why the field shortcut holds.
The rule is for ladders that lean on something: extension ladders and single straight ladders. A stepladder stands on its own legs, with a metal spreader or locking device holding it open, and has its own limits further down this sheet. Scaffolds, guardrails and the rest of the access picture are on falls, ladders and scaffolds.
Talking point 02
The setup on one drawing
Working length runs along the rails; the base is measured on the ground from below the top support. Four to one puts the ladder at about 75 degrees.scroll →Talking point 03
Base distance for common working lengths
One quarter of the working length, rounded for the tapescroll →
Working length
Feet out from the top support
8 ft
2 ft
12 ft
3 ft
16 ft
4 ft
24 ft
6 ft
28 ft
7 ft
32 ft
8 ft
Working length is shorter than the ladder's overall length whenever the rails run past the top support, as they do at a landing.
Talking point 04
The other numbers around a ladder
3 feet past the landing
When a portable ladder is the way onto an upper level, its side rails reach at least 3 feet above the landing so the climber has something to hold through the step-off. Where the ladder is too short for that, 29 CFR 1926.1053(b)(1) accepts a top secured to a rigid support plus a grab device such as a grab rail.
A 19-inch break
29 CFR 1926.1051 requires a stairway or ladder at any break in elevation of 19 inches or more, unless a ramp, runway, sloped embankment or personnel hoist already provides access. Where 25 or more employees use it, or traffic runs both ways, the answer is a double-cleated ladder or two separate ladders.
The top of a stepladder
The top and the top step are not for standing on, under 29 CFR 1926.1053(b)(13), and the rear cross-bracing is not for climbing unless the ladder is built for use from both sides.
Hands free on the climb
The same section bars carrying any object or load that could make the climber lose balance. Tools ride up on a belt or a hand line.
Fixed ladders at 24 feet
A fixed ladder with a climb of 24 feet or more needs fall protection of its own: a cage, a well, a ladder safety device or a self-retracting lifeline (29 CFR 1926.1053(a)). It is a separate trigger from the 6 feet on fall protection trigger heights.
Talking point 05
When a ladder leaves service
A competent person inspects ladders periodically and after anything that could have damaged one.
A ladder with a broken rung, a corroded part or a missing foot is tagged or marked Do Not Use and taken out of use.
It returns only after repair restores its original design, or it is destroyed.
Each worker who uses ladders is trained by a competent person to recognize these hazards (29 CFR 1926.1060).
Talking point 06
Setups to judge on a walk
Short scenarios from a site walk. Read each one to the end before you look at the answers.
Card 1 of 6 · 0 right
Card 1
During a site walk-through, a supervisor sees an electrician standing on the top step of a stepladder to reach a pipe hanger. What is the MOST appropriate action?
Pick an answer. A short note for each option, A to D, appears here.
ADiscipline may follow later, but reporting the worker does nothing to remove the fall hazard happening right now.
BPrivate coaching is a good follow-up, but letting the task finish leaves the worker exposed to a fall in the meantime.
CCorrect: the top step of a stepladder may not be used as a step, so the unsafe act is stopped at once and corrected with proper equipment.
DA toolbox talk next week is useful reinforcement, yet the worker stays at risk until then.
Card 2
A painter must use an extension ladder to reach trim near an energized overhead service drop. Which ladder should the supervisor require?
Pick an answer. A short note for each option, A to D, appears here.
ACorrect: ladders used where the worker or ladder could contact energized equipment must have nonconductive side rails, which fiberglass provides.
BAn inspection checks for defects, not conductivity; an aluminum ladder stays conductive no matter who tags it.
CWire reinforcement makes a wood rail conductive, which removes the very protection a nonconductive ladder is meant to give.
DRubber feet add slip resistance at the base but do nothing to insulate the metal rails the worker is holding.
Card 3
A carpenter sets up an extension ladder against a wall with a working length of 20 feet from its feet to the top support point. About how far from the wall should the ladder's feet be placed?
Pick an answer. A short note for each option, A to D, appears here.
AToo far out. That is a 1-to-2 setup, which leaves the ladder so flat the feet can kick out.
BStill too flat. That is about a 1-to-3 ratio, not the 1-to-4 that OSHA requires.
CToo steep. That is about a 1-to-6 ratio, and the ladder can tip backward when the user leans back.
DCorrect: Under 29 CFR 1926.1053(b)(5)(i), the feet sit about one-quarter of the working length out (4 to 1), so 20 feet / 4 = 5 feet.
Card 4
An electrician sets up an extension ladder in a busy corridor doorway to reach a junction box, and other trades keep passing through with carts. What should the supervisor require before the electrician climbs?
Pick an answer. A short note for each option, A to D, appears here.
AA lookout may help, but a cart that clips the base can still knock the ladder out. The ladder has to be secured or the traffic kept away.
BCorrect: A ladder in a doorway or passageway where traffic can displace it is secured, or a barricade keeps the traffic away from it.
CA steeper setup breaks the 4-to-1 angle and makes the ladder easier to tip backward, and carts can still hit it.
DA sign warns people but does not stop a cart or a swinging door from striking the ladder.
Card 5
A painter wants to stand an extension ladder on a sheet of plywood laid over soft, sloping gravel. When tested, the ladder rocks slightly. What should the supervisor require?
Pick an answer. A short note for each option, A to D, appears here.
AThree points of contact helps the climber's grip, but it does nothing about a base that moves.
BA loose block under one rail is just another unstable support that can shift or split under load.
CThe ladder already rocks. Spreading the load over plywood does not make a soft, sloped base stable.
DCorrect: A ladder goes on a stable, level surface, or it is secured so it cannot shift or kick out.
Card 6
To bridge a gap between two scaffold sections, a carpenter lays an extension ladder flat across the gap and plans to walk over it. What should the supervisor do?
Pick an answer. A short note for each option, A to D, appears here.
ACorrect: Ladders are used only for their designed purpose. A gap is bridged with a platform or planking made for it.
BThe duty rating assumes a ladder used upright as a ladder, not loaded sideways as a bridge.
CTying the ends keeps the ladder from sliding, but it does not turn a ladder into a walkway.
DA harness can arrest a fall, but it does not make the improper use of the ladder acceptable.
Talking point 07
Setting the feet and the load
Is the 4-to-1 rule an OSHA requirement?
Yes, for portable ladders that are not self-supporting. 29 CFR 1926.1053(b)(5)(i) places the base about one quarter of the working length out from the top support (as of October 2026).
Does 4-to-1 apply to a stepladder?
No. A stepladder supports itself and is used fully opened with its spreader locked. The angle rule is for ladders that lean against a wall or structure.
What load does a portable ladder have to carry?
At least four times the maximum intended load, or 3.3 times for an extra-heavy-duty Type IA metal or plastic ladder, under 29 CFR 1926.1053(a)(1) as of October 2026. Duty ratings printed in pounds come from the ladder's label and ANSI standards rather than the CFR.