Should you build a mother-in-law apartment?

One early morning you shuffle into the kitchen to get things brewing, only to discover a woman in a fluffy robe has rearranged the living room furniture. And she’s now feeding your toddler — who is sitting on your new couch — a third powdered doughnut. Sugar is flying everywhere. Nooooo. But then you wake up, realizing your mother-in-law is in her wing of the house, where she can eat her own doughnuts while sitting on her own cozy chair, positioned right where she wants it. Why? Because you built her a beautiful mother-in-law apartment.

What Is a mother-in-law apartment?

Just as the name sounds, a mother-in-law apartment is a separate living space designed for an extended stay. This built-in option gives aging parents the opportunity to remain independent while living in a safe space. Rather than moving to an assisted facility — which can cost thousands of dollars a month — they have the added benefit of nearby family support and companionship. 

The idea is gaining popularity. Some 64 million Americans were living in multigenerational homes in 2021, according to Pew Research, quadruple the number 50 years before. Here in Utah, more than 4% of households have two generations of adults living together.

What does it look like?

A mother-in-law apartment is more than upgrading a spare room. It’s an extra, fully functional living space within your home. While the size may vary — 600 square feet is average — there are basic features most mother-in-law apartments include.

• Bedroom with closet space
• Full, private bathroom
• Living room
• Full kitchen or kitchenette
• Private entrance

Formally called an accessory dwelling unit, it could be built in the basement of your single-family home, in a detached garage, as an attachment to the main floor or even as a standalone structure. 

Considerations

If your family members will be residing in the apartment for a long period of time, you’ll want to consider how they’ll age in the space. Will they have difficulty walking up and down stairs? Does the tub need grab bars? Should it be wheelchair accessible?

Rules

You should also check your local building ordinances for any specific regulations. In 2021, Utah passed a law (HB82) that requires cities to allow ADUs in at least 75% of single-family residential zones. Still, your city may have rules regarding measurements, parking, distance to your existing home, etc.

Cost

While building a space for your in-laws — or twentysomethings — may sound like an ideal solution, it won’t be a cheap one. If it’s a separate structure, you’ll have extra expenses such as new gas, plumbing and electrical lines. A basement or garage conversion will share walls with your home and could be less costly. Find general contractors on KSL Marketplace who can suggest options and give you pricing estimates.

Down the road

If you no longer need the apartment for a family member, it won’t be wasted space. Earn some extra income by renting it out — as a standard or vacation rental. Don’t want strangers living that close? Use it as a guest home for your visiting adult children (and grandchildren). Young cousins giggling all night? You won’t hear a thing. And if you’re really done with guests, turn it into an office or that art studio you’ve always wanted. Or use it for storage space for all your extra Christmas decorations. Who couldn’t use a little extra room?

Boost the value

Another benefit: When you’re ready to sell your house, it may be worth more. A National Association of Realtors® survey found that 33% of buyers would pay nearly $3,000 more for a home with an in-law suite. Some buyers specifically seek out homes with a mother-in-law apartment. According to the NAR, 12% of buyers in 2020 consciously bought an intergenerational home.

Need a larger house to begin with? Search KSL Homes, where you’ll find both pre-existing and new homes you can customize.