Hi Michael, triangles are 3 points only

When I select the two highlighted in my previous screenshot (they are separated before) and do a boolean union it union them correctly but the middle edge is still there so it's kinda making a join instead of a union :(

Here's 2 buildings exported

https://dl.dropbox.com/u/44982094/buildings.3dm

At first they were in a DXF file that I imported in Rhino, I couldn't export it as 3DM because it was not surfaces so I used two commands (explode) then surface to nurbs or something and that's were it made it into triangles. But then I was able to export them as 3DM.