Young Money

These roommate horror stories will inspire you to sign a 'prenup' before moving in together

When Heather, 22, couldn't make the apartment tour with the two friends she had agreed to live with during her last year of college, she told her friends to sign the lease without her. Heather ended up with the smallest bedroom, and her friends — who snagged two much bigger bedrooms — insisted she still pay the same.

Heather's story isn't unique. Millennials increasingly can't afford to live alone, especially in big cities, so they shack up with either friends or family. In 2015, Trulia reported that 60 percent of people ages 18 to 34 had roommates, a 13 percent increase from 1995.

Choosing to bunk with a buddy often feels safer than living with a stranger, but fighting about money, space and guests — what relationship and etiquette expert April Masini calls "the trifecta" of serious roommate issues — can be even harder than duking it out with someone you met on Craigslist.

That's why we at CNBC Make It, along with our friends at Bustle, created a roommate "prenup" you can print out, talk through and sign before you sign a lease. It sets out expectations in advance and makes clear how you feel about crucial topics like how to split the rent, how to deal with pets and weekend guests, and whose turn it is to buy toilet paper.

Click to enlarge or drag to your desktop to print!

The prenup can protect your friendships, sanity and credit score. That's why more experts are suggesting that formal roommate agreements are a smart idea.

"When multiple people sign a lease, they're each responsible for the entire lease," real estate attorney Toby M. Cohen told Brick Underground. "If someone says, 'Go f--- yourself, I have a job in China,' good luck collecting. Unless you have an agreement spelled out, you have to pick up the slack."

"People don't sue over walking the dog," Cohen says. "But people do sue over, 'You left me on the hook for $30,000 of rent.' That's a legitimate claim."

A prenup could help keep roommates out of court, and from being at each other's throats, since it helps you work with facts, not assumptions. Heather, for example, assumed she could trust her friends to keep her best interests at heart when signing the lease. Masini says that was Heather's first mistake.

By not insisting to see the apartment before signing on to the lease, Heather "gave up her vote," says Masini, adding that at any time before the lease was signed, saying "no" or working out a fair rent agreement was an option. Since Heather didn't speak up before the lease was signed, she gave up her leverage.

Similarly, Billy, a 30-year-old making $48,000 a year, could have used a prenup when he shared an apartment with a bunch of guys to help ease the high cost of living in Boston. One of his roommates bought a $900 dining room table and gave Billy a bill for $250, "his share" of the cost.

"We hadn't even talked about furniture," Billy tells CNBC Make It. "He also took the table we all paid for with him when he moved out!"

A lot of times, Masini explains, people blindly trust that their good friends will also be good roommates. When you get into a situation like Billy's, you're faced with the decision to either have an awkward conversation about money after someone has already invested in a big-ticket item or to throw down $250 and set a dangerous — and expensive — precedent.

Beyond money, there's also someone's lifestyle habits to consider. When you share space, your pal's habit of playing guitar in the living room every night at midnight might seem less quirky and more horrifying.

Alexis, 27, learned this the hard way. Her roommate was a night owl, constantly banging around in the kitchen and leaving lights on. One Tuesday at 2 a.m., she woke to the sounds of her roommate hammering up some art.

"If I ever asked her to be quiet," explains Alexis, "she'd say, 'I don't know why sleep is so important.'"

There's a reason many colleges have incoming freshman fill out questionnaires about their habits; it helps them better sync up compatible students. If you're early to bed and early to rise, you may want to steer clear of someone who feels most productive late at night.

Another question you may want to ask: Does your potential roommate have siblings? The answer matters, Masini says.

"People who were only children or who never shared rooms or common space with siblings will have a different view of a shared apartment than someone who grew up in a house where space was less sacred," she explains.

All of these conversations are easier to discuss as theoretical problems using the prenup than as real issues after your boundaries have been crossed.

After all, Masini says, passive aggressive behavior becomes pretty common among roommates, and it can become toxic fast. When Molly, 28, was fed up with her roommate's dates always eating her food, Molly addressed the problem by venting to everyone but her roommate. At home, she just slammed doors and glared.

Having discussions about key issues in advance will save you sleepless nights as well as money and even friendships. You'll go into living together more protected, with your eyes open and with the knowledge that you're all, literally, on the same page.

From splitting the check to DIY adventures, "Young Money" helps you navigate tricky financial situations.

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