Sounds like whatever program you’ve used to import it into UE4 it’s imported it as a single UV wrap.
What program are you using to model the building?
Edit: Also you can try Revit Architect demo if you want to model real scale houses/buildings to codes (example ?v=QGScnVZwiXs) it’s very easy to knock up a quick house/building even if you don’t care if the bathroom door swings into the toilet and closes on a light switch 