Quote - dvlenk6 -
*"Check the mesh before exporting to make sure that there are lines connecting the vertices between corners. Like around that doorway and on the front of the doorframe.
Basically, check that the mesh is made up entirely of either quads or triangles."*So is it possible to fix this this in carrera ? 
I see in one of the menus (the vertex editor?) you can convert a shape to facets or primitives.

You could try 'model' -> 'triangulate n-gons' in the vertex  modeler. It will make all the n-gons into tri sets. I prefer quads myself, but tris are much better than n-gons...

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