How to create a family built from walls and other system families?

[Anonymous]

I’d like to build a family that is composed of walls and roofs.  I don’t want a model-in-place for this.  Is this even possible?  I haven’t been able to find a way so far.

[L.Maas]

Walls and roofs are system families. This means they never can be part of a loadable family.

Depending on your needs, as alternative, you could look at creating groups or assemblies.

[Anonymous]

This is not entirely true. There is a work around or hack where by you can save an in place family(wall category for instance) out as a group, and then change the file type to a rft file. here are a few links which explain it. 

maybe you can then nest a "roof" family into the "Wall" family.

The family template is still however built like a normal family with extrusions etc, it justs has the object styles and categorys of a wall system family etc.

This may not be what you are looking for but may help. Im sure if you google this idea you will find more info on it.

http://screencast.com/t/49haf43mtt

http://whatrevitwants.blogspot.nl/2011/07/save-in-place-family-as-rfa-for-use-in.html

http://danielgijsbers.blogspot.com.au/2014/03/revit-loadable-system-families.html