I'm also interested in learning some more about this. I'm single, and in a position within the next few years to purchase a first home. Of course, homes have more than one bedroom, and most SFR in this area have at least 3, so I would likely use at least one as a rental space. Hopefully I would have a friend stay there but it may be a stranger. Are there any special modifiers beyond what are normally considered for a rental? Assuming I can calculate the real cost of the dedicated square footage, and a fraction of the shared space, and both profit on that and come out either cheaper than my current rent, or with more amenities (for me a yard with a garden). Is there anything in particular about renting a room or similar arrangements that are commonly overlooked?
I do have a friend who bought a home and rented rooms out. He had friends in town who had just recently graduated college with him, so they trusted each other and got along well. He had a steady supply of reliable renters for many years... still having to deal with them moving out, but knowing ahead of time, and no behavioral or property damage issues.
To the OP, yes the financial part is fairly simple. What are your expected returns from the rental, versus what is the cost per month of purchasing the extra space including all interest, expenses, vacancies, utilities etc. Don't forget to a least make some attempt to place a value on privacy and solitude for your family. You don't mention much at all about your family. If you have kids, it could be weird having a stranger in the kitchen all the time when the little one goes for juice. Same if you and your spouse want a nice quite evening and your renter has a friend over drinking beer and playing X-Box, or is knocking the headboard against the wall when your mother in law is visiting. If there's anything else I have overlooked I would love to hear it.
