Plugin for u-turned staircases

Do you know of any plugin that could make a U-turned staircase, or help in making one?

If searched and found a selection, but none support a U-turned staircase.

As with many of your other requests, this isn’t difficult to do with the native tools. But since you need an extension instead. Here you go: Instant Stair

If you have any suggestions for reading using native tools for creating a stair with a U-turn, please let me know. I guess the basic idea if I’m not completely mistaken is to design the steps in 2D and then push them out.

So, can you produce a plan view? Seems like a great starting point.


Not really, I need to come up with a way to calculate and draw it.

Well, stairs begin with knowing the total rise. Once you have that you can calculate the rise and tread proportions. Consider code requirements as you go though.

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Stairs design is an art as much as a science.
Your local authority codes will have their own rules, but most agree that the rise/going[tread] of the stairs must meet certain limits, and that the tread of any step that tapers has a maximum angle of taper between nosings, and has a minimum internal tread value -is say 2-3" [50-75mm] depending on the building type - e.g. domestic or public etc etc…
So it is NOT a simple question…


Also there will be local rules about handrails and guarding for stairs and landings - typically trying to prevent users [including small children] falling to their deaths from a height, or otherwise becoming trapped and suffering catastrophic injuries - e.g. children’s heads becoming trapped in ill conceived baluster designs, and breaking their necks !


Stair_Code_IRC_2006.pdf (1.4 MB)


In the US the IRC or IBC will give you all the information you need to know with regards to stairs and the code that regulates how they should be built.

My wall plugin does have a stair module but it is currently only for straight runs of stairs.

If I could find the time I could probably spend at least 6 months to a year just developing the stair module of this plugin further, there is so much that can be done with stairs, lots of details, lots of permutations.

International Residentional Code: photo 4 specifies a minimum headroom of 6’8" which equals 2.032 m. Often not enough!
Our code here (the Netherlands) specifies a minimum of 2.3m for new domestic functions.

Why that much? Consider walking down requires “a little more” free room than walking up the stairs. This can easily add an extra needed 10 cm to the persons own length.

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I agree wholeheartedly @g.h.hubers

As @TIG said…

• One cannot design a real stairway without full knowledge and comprehension of the applicable codes.
• With that, SketchUp’s native tools are all that’s necessary to model the stair.

Aidan Chopra produced three stair modeling videos, each demonstrating a different technique.
Modeling the stair merely requires understanding and practice with SU’s native tools.

1) SketchUp: Making Stairs: The Subdivided Rectangles Method

2) SketchUp: Making Stairs: The Copied Profile Method

3) SketchUp: Making Stairs: The Treads are Components Method


This gives you the rules (Finnish code):

The rule-based stair creating systems are mostly beasts to use and make you writhe on the floor in agony. I haven’t used one for SketchUp but I have enough experience of the stair tools in Archicad and Revit. It is much more fun to make the basic calculations first and then model the thing from scratch in SketchUp, especially if the stair must fit into a difficult space and have winders and such. Calculate the number of treads you need and draw the 2D plan first.

BTW, avoid building a stair with winders if possible. If there is room, build a landing instead. It is much more safe, and people can use the upper floor even when they get older.


@Anssi, on your opinion what is the minimum depth of a landing? The reason why I ask is that I’m thinking of whether one could fit (probably it wont…).

That’s a very good reference.
Thanks for sharing,

We are talking about a residential stair inside a single-family dwelling, right? In that case it should be as deep as the width of the stair (850 mm according to code). In other stairs there must be room for a person to be carried on a stretcher.

do doors open over the landing reducing available space?

that also makes a difference…


Don’t overlook Appendix Q to the current ERC! It has different requirements in specific situations, most having to do with access to sleeping lofts in small residences. Note Appendix Q is optional and only applies if your local Authority Having Jurisdiction (aka the 800 lb’300KG Gorilla) has adopted it!

Doing this on the road, don’t have time to find a link to Appendix Q.

Slightly off topic, but in mathematical terms, how does one define a stair with one U-turn? E.g. in the image below there is a 100mm thick non-stair section in the middle and a smooth curve that runs along the stairs. Each step is perpendicular to this curve and the distance in the direction of each step to the centreline of the non-stair section is a constant, say alpha. Assuming this, for a given space reserved for the stairs, alpha defines the stairs.

Am I on the correct track here?


(source: RUDUS Elemento 7 stair, which are available in a few different sizes, hence the need to for custom concrete stair)

The line with an arrow might be considered the “walk line,” i.e. where the center of a person passes while actually walking the length of the stair. You try to have more or less consistent tread depth along the walk line. You wouldn’t walk too close to the inside of the winder because the treads are too shallow. In fact, where I am, you can’t have less than 6" at the narrow point, plus another minimum 12" out from there, so that stair wouldn’t be permitted here, at least with that many risers. Ironically, spiral stairs are allowed to come to a point, so the other alternative is whether a spiral (helical) stair will fit. Not ideal if it’s the only way to move furniture, but I’ve done it where it was the only choice.

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