Thursday, January 12, 2012


So last weekend I was playing on the stairs again.  This time I wanted to extend my use of the system stair tool.  No fancy conceptual massing tricks allowed.  So the obvious place to start was the spiral stair that I did a couple of posts back.  It turned out that I could create something very similar.  Slightly less control over the shape of tread, but much easier to place 2 balusters per tread, which is more realistic in terms of safety, regulations etc.

The support brackets are of course modelled as railings by creating a customised baluster family.  The stair therefore has two railings, one set to two balusters per tread, the other to one.  I will return to my adaptive stair shortly and demonstrate its ability to offer much more variety in tread design.  In the system tool you only have a single riser line to define the shape of the tread, but in my adaptive family you can basically model any shape of tread you like.

So the next little exercise was to explore different tread shapes using the system stair tool.  I made an elliptical stair and gave it treads with an "S curve".  This is quite straighforward but you need to set your geometry out carefully.  I drafted it first using detail lines, then traced over with the pick option.  The second stair is even simpler to make, but an interesting exercise all the same.  The bottom few risers are splayed, and the boundary on one side has to step and splay.

This made me think of Michelangelo's famous stair in the lobby to the Laurentian library.  I took this step by step (to coin a phrase) starting with a straight flight and progressively modifying it.  This is often a good approach so that when you inevitably receive the "can't make monolithic stair" message, you can go back to the previous stage and try again.

Eventually I was able to model something fairly convincing and then I just had to quickly rough out the tall square room that surrounds it.  I will do another post on this once I have developed it further.  Had fun with the balustrade too, all done with the normal railings tool, 2 different custom balusters, (one set to be a post at beginnings and ends) and one custom handrail profile (the bottom one is rectangular)

Just to polish off the weekend I decided to try making an ampitheatre.  Looking through my archive I came across the Theatre of Marcellus, also in Rome.  This turned into a fascinating exercise in stairs and radial arrays.  I simplified the geometry a bit so as to make the most of the array tool.  Worked like a treat.  I love the way that arrays in Revit remain "alive" so you can adjust your design as it develops. 

There are 4 or 5 different radial arrays to make up the seating and the access stairs that fit between the wedges.  For each one you keep adjusting the radius and the number of elements. Also by tabbing in to a single element and editing that group, you can adjust the instance properties of that stair, (where it starts & finishes, desired number of risers)  This was a very powerful way for me to explore the way a Roman theatre works. 

Again the surrounding structure is a possible future post, but you can get a glimpse of the way this is also largely composed of a series of live radial arrays that allow you to adjust the spacing and size of archways, column arrays etc until you are happy with the proportions and relationships. Parametric modelling at its best and all very basic Revit stuff that's been hardwired into the programme since forever.

Lest you think I am giving the stair tool to easy a ride let me finish with some grumbles.  We all know that monolithic stairs don't work properly.  They don't join to floor slabs (which is an absolute paint in the posterior) and if you want curved risers, be careful not to curve too far or they will start to cut into each other.  As for sketch mode.  It is very clever, but sometimes it just does its own thing, especially when you have a blue "run" in there.  Intermediate risers don't need to be cleaned up, which is a time saver, but make sure you clean up all the corners.


  1. True spirals usually wrap back over themselves so often it is necessary to model them as two stairs that stack. While a stair sketch will technically tolerate creating a "run" that overruns itself, editing them and adjusting them can be a nightmare. Two separate stairs and sketches makes it a little easier. We'll have to see what the future holds ;)

  2. Hi
    First Tanks about about your blog
    and just some questions :
    How i can make this pattern ?

    And what about the random ?
    Just use Hexagonal pattern is enugh?
    sorry about general questions!
    Best Regards

  3. Thanks Steve

    I didn't realise that it was even technically possible for a stair to overrun itself. I know I tried to do this long ago and failed miserably, so it's been the "2 stair" approach for me ever since, not just for spirals, it's often necessary in a multi-storey building where the ground floor is significantly higher than the typical and a dogleg stair will need to turn back on itself to reach the ground within the same shaft

    Dear Anonymous

    Thanks for the interesting question. I will try to do a post on this soon. It seems that the panels are basically rectangular with each one being laser cut to a different pattern of perforations. We did a project a bit like this using 4 or 5 different curtain panels, created a curtain system by face and swapped in the panels we wanted so that the transparency increased progressively. Revit issues are one thing, real life buildability is also something to consider for this kind of work.

  4. Dear Andy Milburn
    Thanks for your graet posts!
    can you upload video instead of image , in youtube or Screenshot!
    I think. it's easier and useful more!
    that's fantastical about your tecinc
    Thanks for your blog

  5. Videos are on my "to do" list. It's been a big learning curve for me over the last few months as this blog has developed and I hope to continue improving. Thanks for the comment, it provides an extra incentive for me to get my ... together.

  6. For years, wood columns and balusters of all sizes and complexities have been used as porch posts, cabinet accents, newels, spindles, and railing supports.



I've been getting a lot of spam so had to tighten up comments permissions. Sorry for any inconvenience. I do like to hear from real people