Wood Designer forum
October 4, 2012
Sorry that Michel couldn’t get back to sooner, but due to unforeseen circumstances he has been tied up on other things, so I’m replying to your last question for him.
Stair Designer is programmed in Paris France to suit the European way of calculating stairs. This means that the stairs are calculated from the general stair well dimensions and that all treads have the same going along the tread line.
The constraints used in the US as you described in your video are not dealt with by the program. It’s possible to create a stair with a minimum step collet by manually moving step nosing but the program will maintain the constant “going” along the treat line. Winders will be calculated to spread over a certain number of steps which will automatically create a safe stair but not necessarily compliant to US regs. as you describe them.
We do have several professional US stair builders using the program but we are aware that this is not ideal for the US market. This is why we offer a free download for testing before you commit to buying the program.
Today is September 7th and I am getting a bit uneasy about the software as well as the support I paid for. If your software can’t create a stairway with winders compliant with codes in the US (and possibly elsewhere), I have no problem with that. Just make sure your website provides that warning so people don’t waste their time or money on a product and/or service that isn’t workable in their country.
Attached is a video explaining winder codes in the US which are based on the International Building Code…
August 7, 2014
I have also posted the question to the developers. As soon as I have an answer I will inform you. Due to the holiday period, it can take more time before I get a reply but I will follow up and inform you.
And to add to the confusion regarding terminology and code interpretation, the drawing I posted a couple of replies ago (found on a site making software for stair design) , calls for a minimum 6″ tread depth for winders… but the verbiage is clearly “width” on that diagram, yet the correct terminology would be depth, just like in tread depth. Also. they are showing a carpenter’s square perpendicular to the riser picking up a minimum 10″ tread depth. This would be correct if the code intent was to measure tread depth perpendicular to the riser on winders, but that isn’t the case. The code wants the tread depth to be measured at the walkline…
322.214.171.124 Tread depth. The minimum tread depth shall be 9 inches (254 mm). The tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread’s leading edge. The greatest tread depth within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm). Consistently shaped winders at the walkline shall be allowed within the same flight of stairs as rectangular treads and do not have to be within 3/8 inch (9.5 mm) of the rectangular tread depth.
Winder treads shall have a minimum tread depth of 9
10 inches (254 mm) measured between the vertical planes of the foremost projection of adjacent treads at the intersections with the walkline. Winder treads shall have a minimum tread depth of 6 inches (152 mm) at any point within the clear width of the stair. Within any flight of stairs, the largest winder tread depth at the walkline shall not exceed the smallest winder tread by more than 3/8 inch (9.5 mm).
I haven’t done the math yet, but it would seem intuitive that the code code be achieved regarding the same tread depth at the walkline (3/8″ max deviation between largest and smallest winder) with 2, 3 or more winders dependent upon the arc length (pole diameter for a visual reference) they are wrapped around.
So based on those two drawings and using a 9″ tread depth, can we create a stairway in your program that will have six symmetrical winders creating a 180 degree turn? There would be an approximately 20″ space between the lower and upper stairwells 2(6 + 6/square root of 2) = 20.49 I may have to live with that based on our code requirements of consistent tread depth (no more than a 3/8″ deviation) for all winder stairs at the walk line. So i must turn through each 90 degrees with the same number of steps as the next 90 degrees. In other words, the 180 degree wind must be made from mirrored 90 degree segments.
Now I see the majority of my problem… I have a demo version of the program so I can’t see individual part dimensions, just flight dimensions.
More importantly, why do you have a 2-1/2″ nosing on the steps you created? I would think 1″ overhang is standard.
The steps you created would not work here in the US as they are not symmetrical. Our codes are based on the International Building Code so sooner or later your program will need to address this. Screen shots below show what I would call tread depth, you are calling tread width. Width should mean only one thing, the width of the stair. Though the picture shows 10″ tread depth, in the state I live in, the depth is 9″ minimum.
August 7, 2014
No problem, I understand that you need a quick answer and this is what we provide mostly. Current period can create some delays but we try to avoid them.
The thread width in stairdesigner is what you can call the going ( distance from nose to nose ). The tread width and depth are set in the step dimensions.
To change the tread line just select a flight. It will colour dark when selected. On the right side, you have your property screen and there you can locate the tread line parameter which you can adapt.
I am going to apologize for my impatience. I see that there are only a few of you providing service and your available hours are most likely limited. That being said, I appreciate what you have revised and I need to learn more about the program before saying this will or will not work. Big thing here in the US is following codes, and most all reputable stair builders would require a program that would create code compliant steps. But like you said, the program may just work fine if certain dimensions are tweaked. Once I get a better feel for the program, I will get back in touch with you.
Just for my education, you mention tread width… not being a stair builder, I would associate width with the width of the stair (36″) and use the word depth to describe the available footprint from the riser to the nosing (8″). but it appears that my terminology may not be what the experts use.
How did you set the walk line? If it is in one of the instructional videos on this site, then don’t bother answering that. It would be up to me to spend my time finding that for myself.
August 7, 2014
I have made some changes to your stair. Set the walking line at 12 inches and the tread width becomes 8,16 inches. The 6 inches width of the step should be pretty close on that one. Stairdesigner is currently not designed with respect to US building codes but the stair can be worked on to achieve the needed results. The only way to get a better tread width is to add length to the flight or remove a step that will get you 8-inch riser height and 8.78 inches tread width.
I see that you have not added a landing step yet. This also affects the tread width.
Let me know your findings on this one