http://www.scriptspot.com/3ds-max/scripts/mw-roofgen 

MW RoofGen is a spline and roof angle. It makes it possible for us to make it easy for you to make it easier for you. It is a good idea to try it!

Version 1.3

-Added ability to work with a few splines
-Fixed some bags and errors
-Just need to select required splines
-Result to converted to EditablePoly
-No cupping in the bottom of the roof
-Roofs created in positions of splines by height

Version Requirement: tested in 3ds Max 2014