Kriscidious's tutorials are good; and ultimately you will need some very good model organization: Make your floor plan a component. What you include in that component depends on the flexibility you want/need. You can Copy that floor plan component off to the side and edit it, after your edits are finished, erase it, your plan in the house will be changed as long as you didn't select "make unique". there are other ways too but this technique is consistent for me.