small problem with export model

hello everyone

here’s what bothers me realize I board a house with blender ( addon archimesh ) when I build my house in EU4 I board black box that surrounds the door is the window if I wanted to know what that one can help.

I can look for a ais made ​​and I believe it is because of the hole that generates a box in EU4

so when your project totally finished and export to FBX import into blender and simply remove by hand the black box for now this is the only way that I find