The rise of multi-generational households has been pretty significant in recent years. In 1980, just 12 percent of people lived in homes with three or more generations. But with the cost of assisted living and nursing homes constantly rising, more and more older Americans are moving in with their children and grandkids. There's also been a rise in adult children moving back home with their parents.

As of 2019, one in five Americans was living in a home with two or more adult generations. And, 41% of Americans buying a home were considering accommodating an elderly parent or an adult child.

When grandma and grandpa move in–or when an adult child moves back home–it's common for them to take a spare bedroom upstairs or in the basement. But there is another option that can give more space and privacy–a mother-in-law suite.

What Is a Mother-in-Law Suite?

happy family grandmother old mother mother-in-law and daughter-in-law daughter cook in kitchen, knead dough and bake cookies

A mother-in-law suite has a lot of common names like accessory dwelling units, multi-generational units, secondary suites, or granny flats. In Hawaii, they're known as ohana units. In the Southwest, they're called casitas.

Basically, a mother-in-law suite is a private living area that you can add to your home or on your property. It's more than a guest room, but it's usually not as big as a guest house. Essentially, a mother-in-law suite is a separate, independent living space that provides comfort and privacy away from the main house. They are easily customizable for the specific resident. But usually, they include at least one bedroom and a bathroom.

A traditional in-law suite can be connected to your home or it can be a separate structure, like a converted garage or an outbuilding on your property with electricity and plumbing.

Many mother-in-law suites have their own separate entrance, and some have their own living room and kitchen. If your parents or adult children are moving in long-term, a mother-in-law suite can be the perfect solution for multiple generations living together under the same roof.

How Do You Add a Mother-In-Law Suite to Your Existing Home?

mother-in-law suite addition over garage

With more and more families renovating their homes to accommodate aging parents and adult children, builders and renovation companies have come up with numerous ideas for adding a mother-in-law suite to an existing home.

Oren Farkash, CEO and Owner of South Land Remodeling Inc. told Homelight that the ideal scenario for a mother-in-law suite is utilizing the garage space. This is because a garage is usually off to the side of an existing home or completely detached.

Since "comfort and privacy" are what clients are looking for, reconfiguring the garage will meet both of those needs. But, you don't need a garage to create a mother-in-law suite.

“Sometimes we need to get creative and use an existing bedroom that is somewhat private, preferably in the back of the house," Farkash explained. "This gives more options with the design and reduces disturbance of other rooms."

A bedroom in the back of a home also gives the option of expanding the space into the backyard for more square footage. This would make it easier to add amenities like a walk-in-closet, a bathroom, and a separate entrance.

Mother-in-law suites are not always additions, though, as any people who are building new homes are including them. More and more builders are offering specific floor plans that will accommodate multiple generations living under the same roof.

A Mother-In-Law Suite Can Have A Number of Uses

Small green and orange guest house in the back yard

You don't have to have your parents or adult children living with you 24/7 to add a mother-in-law suite to your home. They can also be used as an office, yoga studio, man cave or she-shed, or any other use you can think of.

They can also be a source of income. Depending on where you live, you can earn some cash by listing it as a rental on Vrbo or Airbnb. Travelers are opting for Airbnb over traditional hotels now more than ever. And, if you live near a popular vacation destination, the suite could possibly pay for itself. Just make sure that short-term rentals are legal where you live.

When it's not being rented, you can easily use it as additional space for when you have visitors. A mother-in-law suite will not only be convenient for your family, it could also be a great investment. If you ever want to sell your home after adding it, you might be surprised with the return.

Lori Adams, a top real estate agent in Buffalo, New York, says that she recently listed a house with a one-bedroom mother-in-law suite at $145,000. She says the owner ended up with 14 offers, and the home sold for $191,000.

You're Ready to Add a Mother-In-Law Suite, Now What?

Foundation and first floor of home addition framed and covered with osb (oriented strand board)

A mother-in-law suite might be the perfect solution for your family. But, we have to warn you that it might not be legal where you live. City and municipal zoning ordinances and permit requirements can get in the way when you want to do this type of renovation.

The most important factor is usually size. For example, the city of Portland has an ordinance that limits "accessory dwelling units" to no more than 800 square feet.

When planning an addition or redesign, you have to consult with a professional that knows the local rules. You also want to think about how to add the suite with the fewest structural adjustments. Consider adding on to an existing half-bath or small bedroom. And make sure it's in a place that offers easy access.

How Much Does It Cost to Add a Mother-in-Law Suite?

Green house with orange doors and detached guest house in the back yard

Of course, budgets will vary based on your specific needs and tastes. You can renovate a garage on a budget of $10K to $20K. But, it does get more pricey when converting a walk-out basement or adding a new accessory dwelling unit. Those types of renovations can cost $40K or more.

The best thing is to know what your goal is for the mother-in-law suite. How are you going to use it? Who will live there or use the space? Do you want rental income? Before you spend a dollar, know what the purpose of the space is and discuss budget options with a professional.

You can manage the cost of the project with material selection and design. Kitchens will drive up the cost of a project because of the appliances and finishes. But, there are ways to get the job done on a budget.

Adding a mother-in-law suite to your property could be the perfect solution for your multi-generational living situation. Or, it could be a great way to generate extra income and increase your property value.

Before you make this smart investment, be sure to consult a licensed professional so you know the zoning regulations where you live. They will also help you create the right mother-in-law suite for your needs and budget.

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