Automatic roof slab creation


hi guys,

i’m having a problem trying to create a roof slab on top of an existing one. the original is sloped and i want to have an area that copies that slope but sits on top of it and has equal thickness.

i tried two different approaches:


  • create Extrusion that cuts through the roof surface.
  • take the resulting surface and use it’s points to alter the roof with Roof.SlabShapeByPoints
    -> Result: Revit tries to find its own way of generating the faces and they’re wrong most of the time.


  • create Extrusion that cuts through the roof surface.
  • thicken the resulting polysurface and push it into revit with Springs.FamilyInstance.ByGeometry as a mass Family.
    -> Result: works quite well, sadly some faces arent transported to Dynamo so there are holes in the mass which cant be edited/closed later on.

Do you guys have any hints how to approach this?
Attached you’ll find a png for each approach and also the revit 2018 file in my gdrive.
thanks for any help!!

Dyn_roof_A.dyn (22.8 KB)
Dyn_roof_B.dyn (18.1 KB)