I'm just working on a roof of a large house and in 3D wanted to see thru to the walls underneath the roof without hiding the roof. I used the Demolish tool to make the roofs transparent -- and tweaked the Phase - Temporary material to something other than the blueish hue that it is by default.
This is allowing me to figure out to make the roof line less ugly on this project
...then you'll have to undemolish the objects to bring them back to life.