Tuesday, 26 October 2010

How to stop Revit floor slab edges from moving.

Some of you may already know this workaround as it does go back a few years but it’s something that I have just stumbled upon which would of saved me a lot of time on previous projects.

The symptoms.
  • Having groundhog day checking and double checking your slab setting out?
  • Wondering why one edge of the slab appears to of shifted whilst the other side remains in the same location?
  • Spending days wondering who is sabotaging your slab setting out and perhaps more puzzling why someone would be doing this?
  • Getting sick of having to edit the slab sketch and YET AGAIN lock it to a gridline?

 The problem:
Floor slabs sometimes feel the need to try and be helpful by shape shifting themselves when walls which are adjacent to their edges get moved. If the wall moves the slab edge moves. You can try any of the following methods to combat this behaviour to no avail. Pinning, locking sketch edges, locking dims, isolating on separate workset...All of which won’t work.

 The solution:
Simply put the slab(s) in a group and it will no longer be able to shape shift..
A very simple but very handy workaround. I’m guessing the same thing applies to roofs and ceilings although i haven't tested it on them yet.


  1. Hello .. Scratchpad Revit ...
    Joe Stott ...
    Luiz Calos_lcchvacr ... Said ... I share with your blog, I liked the profile of your post, excellent early work on Revit, Revit Mep my area is anything but of Revit.
    "The Less is more"
    My compliments.

  2. Thanks for the great tip. Also interesting to note that there used to be a bug whereby slab edges on the opposite side to a wall might also move with the wall. This was fixed in v2010, and we find floor slabs a lot more stable now.
    Tim Waldock,
    PTW, Sydney

  3. Hi Luiz & Tim. Thanks for the comments and support.

    Tim, The bug you mention sounds like the one which used to drive me nuts in Revit 2008/9. I guess its better in 2010 onwards but its still trying to be too clever for my liking.

    Thanks again.

  4. Another way is to disjoin the walls from the slab while you are moving them.
    When you start the move command a check box will appear below the ribbon between the constrain and multiple check boxes.
    Ticking this box tells Revit "Butt out, I knows what I's doing. Leave everything where it is thank you very much!!"

  5. Apparently this grouping workaround no longer works in 2014. Under the username SLAB, I created a couple of structural floors, one by picking walls, which of course associated the slab edges with the walls. I created a group containing both floors and put both the floors and group on a workset named STRUCTFLOORS. I saved but did not relinquish the workset, then opened a local under my normal username BRG. The group and floor slab were not editable, still being owned by SLAB, yet moving the walls associated with the floor which was created by picking walls STILL MOVED THE SLAB EDGE. Arrrghhhhh!