Help on Stairs Design


I’m not really oriented on how to make stairs and I’m pretty new to SketchUp (I’m using 2016) as well.

Here’s the spiral stairs. I know there’s something wrong but I can’t quite point it out.

Georgian Stairs Clearance and Opening

Can you post the SKP file?
From looking at it, the floor has no thickness, the treads are too small and you need a hand-rail. Other than that it looks not too bad.


Here’s the cleaned skp file. I deleted almost all but the most important layers.

Untitled2.skp (317.4 KB)

This is not the actual house, though. I just left the first and second floors and the stairs so I can upload it as fast as I can and it can be DL’d faster.

P.S. Apparently the file size increases if I edit anything, even if it’s deleting elements in the file.


I observe that the treads are not horizontal, there’s a pretty big gap between stairs one could easily step in, and, of course, you need to fix all the reversed faces.



Learn to use Model Info > Statistics > Purge Unused…
This removes unwanted dross, and makes the SKP much smaller.

First the good news.

You have made the treads as instances of the same component, so editing one edits all.
This will make correcting things much less traumatic.

Now the bad news.

  1. Modeling -
    The treads faces are all reversed - should be off-white NOT the back-face blue-gray - select them and reverse them.
    The top of the tread is not actually level and has an odd ‘bevel’.
    I suggest you reform the whole tread, drawn ‘flat’, and PushPulled to the desired thickness.

  2. Safety -
    This depends on your local construction-codes and the type of building etc… but…
    Treads should always overlap with a consistent ‘nosing’ of say 25mm/1" - your current treads leave an ever increasing ‘gap’ that’d be perfect for breaking your ankle !
    Treads have a maximum ‘rise’ - say 180mm/7" ?
    There is also a minimum tread ‘going’ at the thin [post] end - typically 50mm/2".
    The tread measured at the tread’s center also has a minimum ‘going’ - say 220-250mm/9"-10".
    The rise:going ratio have limitations too…
    The combination of the nosing, the two goings’ minimums and the width of the stairs itself etc will produce a ‘taper angle’ for each tread… draw it as a simple face in plan to get your parameters sorted before starting making the parts.
    The open [vertical] gap between two treads should not exceed 100mm/4" - this is to stop children falling through - so the rise-4" gives you the tread thickness - it’s unlikely you’ll want to make it as a solid slab, so perhaps a 1" tread and 2" downstand or some other detail to restrict this gap is more logical…

We'll leave the handrails till later...:grinning:


A quick search on the internet will also yield an informative basis for stair layout. It is easier to comprehend the design concept by seeing visual examples of the requirements than by reading about them.

Here is a link to one such search:


To add to the criticisms here, the opening in the upper floor is too small - there is not enough headroom where the stair swings under the floor. It is less than 1,5 m - you need at least 1,9 m (or even more if this is not for a private apartment or if your local code differs from the Finnish one I know).



Is this better?
Untitled4.skp (333.3 KB)


You still have a problem with headroom clearance. You need to consider the actual height of a normal sized person. This stair must have a wider opening that can accommodate the standing height of a normal sized person as he or she moves up or down the stairs. In the U.S. the code requirement for such clearance in commercial or public buildings is a minimum of 6’-8" or 2.03m. Additionally, the individual riser height is too shallow to be effectively safe. The depth indicated is about 5" where that dimension should be between 7" (.18m) and 7.5" (.19m). If the depth of risers is much less than this, a considerable tripping hazard exists when walking up or down.


If your just “sketching” or getting ideas there still is the need for proportions and real space items. Especially when asking for opinions and options. Your door ways, the single room entrance ones wont accommodate a wheel chair but the stair well will handle a golf cart. Normally the two follow each other. Even custom need to follow this. If you do need stairs that wide, extend the opening, stretch the upper railings and curve off the ending corner… You have good work and time invested and that looks like it was just crammed into the space.

Untitled4.5.skp (487.5 KB)


May I directly use your stairs in my original model?


Unfortunately the stair remains unusable from a practical standpoint. See the attached image and take note of the inadequate clearance.


Yes… but use the idea to create it right and the stairs would need an over haul. The floor to ceiling was like 9’ 8" and I deleted some last night and even lowering and re-rotating them 12" the clearance was 5’ 3". I would scrap the stair case as it is in the model, and redo with a:

Untitled4.5.skp (496.3 KB)

This was something quick as an example of how it is a FUNCTIONING staircase. It is not code spec. but to help Ace see design does need to follow function. If they want the steps 74 inches wide so be it, but the step height still has to allow some one 6’ to walk up them. For the original 118 inch floor to ceiling something like this ( just an example not a fix) shows 7 feet instead of the 4’ 4" of the original stairs. Just something to think about and do not paint yourself into a corner, with 2 hours of modeling and then 2.5 hours of redo’s over lost insight.


I’ve adjusted the stairs and the clearance is now 2.3m (which might seem a bit too much but that’s for bringing stuff upstairs)

The individual risers are that wide to allow potentially 15 people to get up stairs fairly quickly.

Untitled010.skp (561.9 KB)


The head clearance is workable now, but is wasteful in that the design is not efficient. More material is required than is necessary to satisfy the desired function. Good design must be mindful of conserving building resources.

[quote=“AceBite, post:14, topic:18577”]
The individual risers are that wide to allow potentially 15 people to get up stairs fairly quickly[/quote]
This is a false assumption. Your circular stair would be difficult to travel up or down because no person would be able to hold onto the handrails as the distance across is almost 6 feet wide. On a circular stair regardless of the width, only one person would be safely able to travel up or down at a time in any event. Also, the riser height is perilously dangerous at almost 10 inches in height. Can you picture the potential issues that could arise when a person wearing high heels or a disabled person has to traverse this stair configuration? Bear in mind that stairs can be the source of severe injury resulting from falls if such stairs are constructed in a way that promotes walking hazards. This is why stair construction is required to adhere to building code restrictions. As previously mentioned, the most efficient ergonomic arrangement of risers in enclosed structures will occur when their height is between 7 inches and 7.5 inches. (The most efficacious height for exterior stair risers where exposure to snow or rain is likely should not exceed 6 inches.) In extreme cases, an interior stairwell riser height of 7.75 inches may be acceptable, but risers should NEVER exceed this latter dimension.

Please recognize that you are not being picked on…I offered much harsher critiques to my former architectural students…however you need to be aware that a bit of research on this subject will go a long way toward advancing your ability to model circular and straight/return stairwell runs.


Correct me if I’m wrong: the risers are the steps, right? And they need to be ~7in (0.18m).

Also, in the case of spiral stairs, does space between the steps need to be a certain distance?

RiserQ.skp (103.0 KB)

I really do not have a problem with “harsh” critiques for as long as they’re helpful.

But also, I have never done anything like this before (like this, i.e. making stairs or anything architecture-related) and neither am I an architectural student and unfortunately, we meet only once a week and since it’s the break I can’t consult her. The idea of spiral stairs just came to me after our last meeting.


No, The Rise is the ‘Height’ of the step.

The step already has a name. . . it’s called the ‘Step’, or a ‘Tread’

You might go back and look through this thread again, and reconsider any links or comments others have already mentioned.

Try to reconfigure your staircase so that the riser height is around 7" or so. this will help you with the head room problems.

Measure some existing staircases in your neighborhood. and count the number of steps. Your configuration has a lot of treads, and there should be a good reason for that. If not, going along with the local standards and code is probably the better way to go.


The risers refer to the vertical portion of the steps between the “treads”. The treads refer to the horizontal surface of the steps that is walked upon.

In a circular stair the dimension of the tread at midpoint should be no less than 8 inches. The optimum tread width at a straight stair should be around 10 or 11 inches. (These are not absolute rules because the requirements will vary depending on the applicable jurisdiction and governing codes.)

In your attached illustration, you asked “What is this and is it needed?” That element of the stair is referred to as the nosing and yes it is a desirable feature. Stair nosings generally overhang the face of the riser by about 1 inch and may have a vertical dimension of 3/4" or 1" for a total riser height of between 7 and 7 1/2" at interior stairs.

I recommend that you conduct a browser search on stair design standards to see common graphic representations of stair requirements. I also suggest referring to the text by Ramsey and Sleeper entitled “Architectural Graphic Standards” which is a primary resource for all things related to architectural spatial requirements.

You will need to consider handrail requirements as well. A minor point to bear in mind when designing handrails: The handrail height should be 34" above the tread when measured from the face of the riser.


Taking into consideration everything that has been correct and done, I’ve decided to switch to a flat staircase. Not only did I discover that spiral staircases require quite a lot of work, but I found them to be quite dangerous. I need a staircase where a person could climb the stairs carrying, say a box, 3’-4’ in height safely.

I do greatly appreciate everything that everyone has contributed but I don’t think a spiral staircase is fit for this model.


I believe that’s been the elephant in the room all along. Congratulations on a good decision.