To use the gable decoration you must use the "moveobjects on" cheat.
Download gable ornament mesh (2 tiles)
I’ve changed my policy about cloning or recoloring my Sims 2 objects. Read HERE for details.
New objects for The Sims 2 are currently in Beta stage. They run safely in The Sims 2, but you should use them at your own risk. Recolored objects will require you to download and install the CEP – Colour Options Enabler that can be found here: