I am trying to create a loop cut on the walls of a section of a house, however, it doesn't go all the way around. Ngons can't be the problem since I'm sure all faces are quads. However, it might be the orientation of the faces? Could it be the way I have a single-faced wall?
Yes, it's the single-faced walls. You have some places where there are 3 planes sharing one edge. The loop tool can't create a loop past these places. You need to model those walls - the ones where you just have a single plane - like you've modelled most of them, as a U shape.