Best way to "push-pull" roof 'surface' to create building?

[IntelCoreDuo]

I often make large models of entire towns where I turn 3D dwg roof "outlines" into surfaces using sandbox tool, then use the great plugin "Fredo6 joint push pull" to extrude houses down past terrain level, which works pretty well even when houses have complex roof shapes.

However, when doing many houses simultanously I often get error messages and need to do the roofs individually instead (even when it appears to have worked at first).
Is there any workaround or different plugin that lets me "push/pull" (extrude) very many (curved) surfaces along the Z axis at once?

[pilou]

JPP is the best one!
Projections by Didier has also a push pull multiple but less sophisticated!

PS I suppose that you have seen that : When you have made one JPP simple or multiple
you have just to make a double click on the following surface one by one for have the same JPP!

Look also Architect Tools by Thomthom for the DWG files inside SketchUp!
It has functions for automatically create buildings from the DWG!