House hacking, splitting single family home into 2 sections

[James Elden]

I'm looking at maybe trying a house hacking setup where I would buy a single family home and split it off but not in a permanent way, such as putting a door in a hallway to section off the front of the house from the back. In the areas where I'm looking, single family homes would cash flow much better, it seems, than a duplex so my thought is that after a year or two I could move out and rent the house as a single family home. For this reason I don't intend to make any changes that can't easily be undone and the back, where I would live wouldn't need to have a full kitchen. I would be making some modifications to the house though, such as putting a door int the hallway that can be closed to separate the units and maybe some other stuff that I haven't thought of yet so I'm wondering what generally is considered the threshold at which this would normally become not legal without permits, etc? I think that the laundry area would be shared between myself and the tenant. I figure this is probably kind of a gray area, so would appreciate any advice. Thanks