Quick answer: For one person making a quick trip, a ladder is usually enough. For repeated access by a crew carrying tools and materials over more than a day or two, an adjustable stair system is faster to set up than a built-up stair tower and far more stable than a ladder.
Ladders, Stair Towers, or Adjustable Stairs: The Real Trade-offs
Most contractors default to whatever access equipment they already own, which is usually a ladder. That works fine for a single quick trip up. It starts to break down the moment a job needs repeated access by multiple workers, tools and materials carried up and down, or more than a day or two on site. At that point it is worth actually weighing the options rather than defaulting.
- Extension ladders are cheap and portable, but they only support one person at a time, do not carry materials well, and get less stable the more they are moved and repositioned across a job.
- Built-up scaffold stair towers are sturdy and code-friendly for long-duration jobs, but they take real time and labor to assemble and disassemble, which adds cost on shorter jobs. Modular towers such as Z-Stack™ cut that labor: pre-engineered modules bolt together and the tower can be craned into place.
- Adjustable temporary stair systems sit in between: faster to deploy than a full stair tower, but far more stable and higher-capacity than a ladder, and built specifically for repeated multi-worker access.
Questions Worth Asking Before You Choose
The right choice depends less on preference and more on the shape of the job:
- How many workers need access, and how often? A single electrician checking a rooftop unit once is a different problem than a full roofing crew moving materials up and down all day.
- What is the roof pitch and height? Equipment that only fits one configuration will not travel well between jobs; equipment that adjusts to different pitches and heights does.
- How long will it be on site? A same-day repair does not justify the labor of a built-up stair tower. A multi-week reroof might.
- How much setup time can the crew afford? Every minute spent assembling access equipment is a minute not spent on the actual work.
- Does it need to move between job sites? Equipment that breaks down and travels easily is worth more to a contractor working multiple active sites than a fixed installation.
The Numbers That Decide It
Whatever you choose, it has to meet OSHA's access rules. These are the figures ATI checks first when a contractor asks what to use for roof access.
| What to know | The number | Source |
|---|---|---|
| When access equipment is required | Any break in elevation of 19 inches or more | OSHA 1926.1051(a) |
| Ladder height above the roof edge | Side rails at least 3 feet above the upper landing, or the ladder secured at the top with a grab rail | OSHA 1926.1053(b)(1) |
| Ladder angle | Base out about one-quarter of the working length (the 4 to 1 rule) | OSHA 1926.1053(b)(5)(i) |
| Temporary stair angle | 30° to 50° from horizontal | OSHA 1926.1052(a)(2) |
| Landings on temporary stairs | At every 12 feet or less of vertical rise | OSHA 1926.1052(a)(1) |
| AdjustaStairs™ heights | 3 to 32 feet, in 6 to 40 step models and 24, 36 or 48 inch widths | ATI brochure (PDF) |
| AdjustaStairs™ weight ratings | 660 lbs (Standard) and 1,100 lbs (High-Access with Support Truss) | AdjustaStairs™ specs |
Why Adjustable Stair Systems Are Gaining Ground
For jobs that fall between a quick ladder trip and a long-term scaffold installation, which is most roofing and elevated-access work, an adjustable stair system tends to be the practical middle ground. AdjustaStairs™ is built around that gap: it is tool-free, adjusts to different roof pitches and heights, and typically takes two workers to set up, with one positioned at the base and one at the top while the system self-levels into place. That means a crew gets a stable, code-oriented access point without treating setup like its own separate project.
If you are outfitting a crew with access equipment alongside other site supplies, ATI Construction Products offers same-day quotes on stair systems, scaffolding, and fall protection equipment shipped nationwide. To see which AdjustaStairs™ model fits your roof, enter the height in the size calculator.