You have a spare bedroom, and your friend needs a place to live. You happen to be short on cash, so you consider having your friend move in.
Keep common areas clean. If you've seen “The Odd Couple,” you know a slob and a clean freak don’t match. Figure out what is an acceptable level of disarray in common areas before your friend moves in.
Discuss rules for visitors. What are reasonable hours to entertain? Talk about your tolerance for loud noises and music. Also discuss overnight guests and how long they can stay.
Get legal. Write up a formal lease. You can find one online or at a stationary store. Chances are it won’t come to the point where legal action is required, but just the fact you and your roommate discussed and signed an agreement will make things run smoother.
Work up a short lease. You may be renting to a friend, but you never really know a person until you live together. A three-month lease, for example, gives each of you an easy way out without ruining the friendship.
Discuss sharing. Your friend might not mind if you borrow his toothpaste, but you might not feel the same. Some roommates share a carton of milk, while others prefer having their own. Discuss whether certain items will be shared.
Set timetables. This step is especially important when sharing a kitchen or bathroom. After all, there’s nothing worse than being late for work because you had wait for your roommate to finish showering. Five minutes can seem like an eternity – and the disagreement that ensues could spiral into a nasty fight.
Talk about taking out the trash. It’s not the most glamorous household duty, but make sure you know in advance who is responsible; otherwise, the trash bags may start to pile up.
Define your personal space. Living with a friend can bring the two of you closer – sometimes too close. Figure out now how you'll ask your friend to give you space in a way that won't create a rift in your friendship.
Decide if pets are allowed. Your friend may not have a pet now, but what would happen if you came home from work and found a dog food dish in the kitchen? It’s better to discuss these rules ahead of time.
Make a plan for shared monthly expenses. Adding a roommate often means a higher electric bill in the summer. Are utilities included in the rent, or will your roommate be expected to chip in?
Discuss tardy rent payments. No one wants to think about a friend stiffing them on rent, but it can happen – especially if your roommate loses a job. Decide in advance what the rules are if your friend is late on rent.
Consider requiring a deposit. Will your friend be responsible to pay for repairs if there’s damage to his or her room? A security deposit can help solve this issue.
The bottom line. Sharing an apartment or house with a roommate can be a great way to earn extra money, but when a friend moves in, it’s important to discuss the ground rules ahead of time to make sure living together doesn't put the friendship in jeopardy.
Gary Foreman is a former financial planner who founded TheDollarStretcher.com website and newsletters. The site features thousands of articles on how to save your valuable time and money, including an article on Living With a Roommate.