Have you ever inspected a property with alternating tread staircases or ship's ladders?

I’m trying to identify what’s worth including in a comprehensive library of commercial/industrial narratives. Anyone ever encounter either of these during an inspection?

Not in my time.

I thought maybe industrial catwalks over various machinery might be accessed by ladders that qualify as “ship’s ladders” but… I don’t know.

Yes, a buddy of mine built an alternating tread staircase to his loft area and it works great as long as you started out on the correct foot.

I ran into one of the same at an inspection and wrote it up as a potential safety hazard.

I have seen and used ships ladders all the time in commercial applications. Typical I’ve seen them in pump/mechanical rooms and a lot on roofs. Last summer I was on a project where new rooftop units where being installed. There was a two sided style ships ladder to go up and over the parapet wall and down to the next level. Nearly all of the anchors had pulled completely out of the brick wall.

Well, apparently they’re not a potential safety hazard as long as they comply with applicable IBC code. I’ve never seen one and don’t know why or where anyone would install one so I decided trying to figure out how they might be built incorrectly and writing narratives to apply to that was a waste of time.

Regardless what that code may say, this was definitely a safety hazard, as far as I, and my client, were concerned.

He said “Man, the kids will love that and will have to be very careful using it.” That was one of my indications that it needed to be in the report as a potential safety hazard, among other things. I wasn’t a code inspector.

Edit: I was focused more on the title of the thread and missed this, Kenton…sorry:

I’m trying to identify what’s worth including in a comprehensive library of commercial/industrial narratives.

Only once and I wrote it up as a safety concern.


Here is the IRC code stating where they can and can’t be used.

R311.7.11 Alternating tread devices. Alternating tread devices shall not be used as an element of a means of egress. Alternating tread devices shall be permitted provided that a required means of egress stairway or ramp serves the same space at each adjoining level or where a means of egress is not required. The clear width at and below the handrails shall be not less than 20 inches.

Exception: Alternating tread devices are allowed to be used as an element of a means of egress for lofts, mezzanines and similar areas of 200 gross square feet or less where such devices do not provide exclusive access to a kitchen or bathroom.

R311.7.11.1 Treads of alternating tread devices. Alternating tread devices shall have a tread depth of not less than 5 inches, a projected tread depth of not less than 8-1/2 inches, a tread width of not less than 7 inches and a riser height of not more than 9-1/2 inches. The tread depth shall be measured horizontally between the vertical planes of the foremost projections of adjacent treads. The riser height shall be measured vertically between the leading edges of adjacent treads. The riser height and tread depth provided shall result in an angle of ascent from the horizontal of between 50 and 70 degrees. The initial tread of the device shall begin at the same elevation as the platform, landing or floor surface.


Thanks Randy. I found provisions in the IBC too. But didn’t want to take time creating narratives for them if no inspectors ever see them.

Lapeyre Stairs alternating tread models are code compliant. I see them everywhere. And I’ve installed them on projects. If I see the Lapeyre logo, I don’t call it out. If I don’t see that logo, I treat them the same as finding older ships ladders in cellars and the rickety stairs you see leading up to the elevator penthouses in 1940’s era buildings in Manhattan: I mention their presence and the fact that at some point in the past they may have been acceptable, but a modern building wouldn’t feature them, and that the stairs should be replaced. That’s it. I don’t say “code compliant” anywhere.

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Hi Kenton, Have seen both but not often. Mainly in older manufacturing structures converted to residence in “revitalized downtown areas.” First saw alternating steps in a hip - mansard roofed structure inside a closet which contained the access to the 3-1/2 foot high crawlspace, then to a “widows walk” cupola structure on the hipped section of the roof. From there, there was an escape ladder to the ground.

I haven’t seen one of these on an inspection, but a picture was really helpful to keep up with what everyone was discussing. Thanks for the learning! I’ll just leave this here:

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Sounds like a secret means of egress, Thomas. :face_with_monocle:

seen it one time, id think its so rare that making a narrative for it may not be necessary. IMO

Ya know something - that may be quite true - War of Southern Succession (war just ain’t civil) it is known some homes in the area were waypoints on the underground railroad.

I’ve seen something similar on a home on the gulf with one of those going up to the widows walk.