You would disturb the tenant's right to quite enjoyment by renovating the house and then you would essentially change the terms of their lease by adding another roommate to share the kitchen, bathroom, living room, parking, etc.

Kitchen and primary bathroom refresh.

We improved interior kitchens and bathrooms as well as filled holes in the asphalt.

We improved interior kitchens and bathrooms as well as filled holes in the asphalt.

Once we closed and started demo on the bathrooms though, it quickly became apparent that we were going to have to do the kitchens as well (as wood rot and some mold had started spreading there too).

Once we closed & started demo on the bathrooms though, it quickly became apparent that we were going to have to do the kitchens as well (as wood rot & some mold had started spreading there too).

IDEAS: abuse of common areas, theft of personal & common possessions, violent behavior, assaoult of another roommate, general friction over kitchen, bathroom, laundry, storage, parking, etc.You may want to create a new post: "What issues have landlords had with rent-by-room tenants?"

After quite some years in the house, market crash and a few other life events, my wife and I renovated the floors, kitchen, garage and basement (adding a full livable space + full bathroom).

Keys are on the kitchen table. 

Guests get a private room and communal kitchen and living/game room.