I ran across a "hack" a while back which I posted on the AUGI forums, and thought I'd add it here too.
We all know that we don't have rft family templates at our disposal for some system families such as walls, roofs, ceilings and floors. But using the following technique, you can create a template for any system family category that is available as an in-place family:
a) In a project, create an in-place family of the category you desire. For example add a simple extrusion, but then do not exit from Family Editing mode;
b) Group the solid;
c) Go to the project browser under Groups and save out this group. Notice that it will be saved as an rfa file;
d) In Explorer, rename the extension to rft. Now you can use this template to create custom parameterized walls for example, that can be re-used from project to project. If you had any geometry that you do not want in your template, make sure to delete it before you rename the file.
It is important to note that you place this family using the Component tool or straight from the family editor by dragging the family, which will be located under the corresponding category. The family itself will not report what category it is when you go to the Family Category and Parameters dialog. See this little video clip for how simple it is to get this done. Enjoy!
RFT Family Template for System Families