My assets dont fit flush

hey guys im very frustrated at Ue4’s difficulties and ran into another big problem. I made some modular house assets in blender, a wall doorway, corner wall, etc. But they dont fit together perfectly in Ue4 like they do in Blender. I tried snapping to grid but they never fit flush like it should. I tried cntrl end to snap to closest grid point but nothing happens when i do that. How can i make my assets fit perfectly and snap to the same grid?

In blender are all pieces in the same scene and exported seperate? Each model exported from blender needs to be exported from the center of the axis’ or this issue you are having can come up