Can you verify that the IFC parameter really drives the material? I would rather imagine that the in-place elements have a type parameter that could just be None or Default at the moment, which could be easy to fix at once. Anyway, if I am mistaken, here are some tips to get started:
- You will first need to collect all the elements that you want to change. There are different methods to select elements: Categories / All Elements of Category could select all walls, and this page could give other clues:
http://dynamoprimer.com/en/08_Dynamo-for-Revit/8-2_Selecting.html - If the material parameter is indeed a type parameter, this thread could help:
Set Type Parameter - If the material to change is structural, see also this:
http://dynamobim.org/forums/topic/problems-with-structural-material-parameter/