Thursday, July 25, 2013

Concrete Steps

Revit doesn't seem to like generating a smooth underside for some stair configurations. A post at AUGI asked about making what seems like simple concrete steps. Yes, they do look simple. The stair (and railing) features sure have a lot of buttons, dialogs and subtlety. There is definitely no easy button unless you are satisfied with whatever the stair looks like after you place two points to create a straight stair. This is the image that the original post included at AUGI.

Years ago I picked on Autodesk because the stair and railing features couldn't easily be used to make the stair in their building's own ground floor atrium/foyer. They've moved since and there aren't any featured stairs now. Coincidence? [evil grin]

Revit doesn't mind creating the steps if we choose the "Stepped" option.

This is what the sketch looks like.

Keep in mind that the "end" of a stair like this needs a riser not a boundary sketch segment. That's why the sketch line at the top of the steps is black, not green. Creating a stair that ends at a landing can be a bit counter-intuitive, I wrote a post about that condition some years ago too, it's called "A Flat Slope".

A little bit later I was doing something with a floor slab edge and it occurred to me that I could use a slab edge profile to create the steps too. So this is the result of a profile family applied to a Slab Edge type and then applied to three sides of the floor edge. I made the top step the floor so I'd have three edges to work with. If I wanted a joint between the floor slab and the step I could just make the top step a floor and create another floor behind it for the building's floor slab.

Here's the section through the steps and floor (on the left) and the profile family in the family editor (on the right).

The section of the step profile shows that it extends under the slab. I did that so I could use Join Geometry between them and clean up the lines between them. Assigning the same material to the Slab Edge type means that the concrete pattern flows between them nicely. The view from below the steps reveals the nice sloped slab edge that results from the slab edge profile. Compare that against the stepped version and this one looks more realistic from a construction perspective.

Now all I need to finish it off is a short foundation wall to close up the space behind the steps and the edge of slab. Something to consider for those little steps you need for your next project.

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