On a simple exterior wood frame wall type, I can't seem to figure out how to activate the base extension property; it is greyed out. How do I activate this parameter so I can extend the exterior sheathing of the wall past (below) the rim joist?
You need to unloack the layers of the wall you wan tto extend. In the type properties dialog, edit the structure of the wall. Click "Modify" in the lower section of the editing dialog. Then you can click on the edge in the wall preview and "unlock" the wall layers. Once you do this the base extension property for the wall will no longer be gray.
Jeff Hanson Sr. Subject Matter Expert Autodesk, Revit User Experience