How to extract the outer "naked edge" of a mesh?

I have a lot of buildings that are mesh. I would like to extract their edge curves. But in Grasshopper with the Mesh edges tool, I managed to only extract the base curve at ground level.

I would be grateful to get any advice/help from you guys!

The E1 output from the Mesh Edges component will give you the naked edges of your mesh.

-Kevin