Part K of the Building regulations states that “The maximum pitch for a private stair is 42°”.
Revit stairs have several checking tools to help make your stairs comply to whatever standards you’re designing to. But there isn’t anywhere that can quickly show you the pitch/slope of the stairs.
Here I will show you how to create a schedule to show you how to do this!
To start with we have to go back (Waaay back for some of us) to school to work out how to achieve the angle from the information that we have!
And who said trigonometry wouldn’t come in handy!
When researching the best way to work out this problem I came across this website and found the following image. Which I found very helpful in explaining what’s needed.
Opposite / Adjacent =
2800 / 3850 = 0.72
Inverse Tangent of 0.72 =36 degrees
Any outcome of Opposite / Adjacent that is under 0.9 will be under 42 degrees.
With all of this in mind. I realised that we don’t really need the full height and run to work this out.
We just simply need the Rise and Tread sizes.
Rise = Opposite
Tread = Adjacent
We can now use this information to extract data in Revit.
Above are simple fields/properties from the stairs, added to a schedule.
We can now use these to achieve our required information.
It’s a fairly simple formula to add within Revit once you know what you’re doing.
We require a new calculated field with the following formula inside.
atan(Riser Height / Tread Depth)
But to do this we have to do a little bit of tweaking within Revit 1st to get it to work. Because we’re dealing with different units we have to do a quick calc to break the Actual Riser and depth down to basic numerical values.
We need to create 2 new “Calculated Values” These will give us the Riser Height and Tread depth broken down into numerical figures and then the atan calculation to get the stair angle.
Once we have these, we can use this figure to work out the atan value giving us the stair angle.
And just like that... we have our angle.
If you want to be extra clever... we could put a “Conditional Format” on the riser angle so that it shows up red If the angle goes over 42°!
I hope this has been ok to follow as I know it’s slightly more complication.
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