Create a Freeform Roof in Revit

Using a freeform shape imported from other programs (horse in this example), we will generate a smart roof in Autodesk Revit.

Steps

Extract Plan – export a 2D DWG floor plan from your Revit model for reference in Rhino. You can export a 2D DWG, but be careful when importing 3D DWG data into Rhino 3.0 (no problem in Rhino 4.0) without using the 3.0 bonus tools. Check the units in Rhino under Tools-Options then either Import or Insert the DWG plan as a reference.
Tip: You can use horse’s dimensioning tools to verify the scale of the DWG insert.
Create Form - we will generate a ‘draped’ form using Rhinoceros. This is done simply by drawing a shape curve and a straight curve, then using the Extrude CurveAlong Curve tool to generate a surface between the curves. The surface can then be transformed into a solid using the Extrude Surface tool. You can import just the surface into Revit, but the flat surface will be difficult to visualize on-screen.
Create Model file – Select the surface or the extrusion, use File-Export Selected Objects and select the SAT file extension.
Generate Revit Roof – In Revit, create a new mass and import the SAT file from the previous step. You may have to adjust its XYZ location before finishing the mass which can be accomplished in plan or elevation.
Once located properly, use the Roof By angle tool to generate a roof using any roof type. Pick the top or bottom face of the mass element.
Finally, select the chain of interior roof as the target.

You can use the same procedure to also create floors, however, any openings in an organically shaped wall must be made in the originating view, i.e. Rhino, PRIOR to importing into Revit.

Be careful when forming an extreme freeform shape in Rhino. Sometimes forms that curve in on themselves will prevent Revit's Roof by Face tool from creating a roof.