Since doors and windows sit in walls, put the section of wall that the window/door sit in on the demo layer, and add a new section of wall on the new construction wall layer.
Erika
Architect, Consultant
MacBook Pro Retina, 15-inch Yosemite 2.8 GHz Intel Core i7 16 GB 1600 MHz DDR3
Mac OSX 10.11.1
AC5-18
Onuma System
"Implementing Successful Building Information Modeling"