>>I ended up using merge to cut the door and windows out of the solid

The model you posted was not solid. So there was some problem during your building,.. either the model was not solid before the merge or the curves you used (with the problems I highlighted) have caused the problem.
Put a sketch together of what you are trying to build and post this,.. we can go through the process of construction. At the moment we are jumping from problem to problem. lets start from base and go from there, if that is OK with you?


regards,