What You Need to Know About Mother-In-Law Suites

What is a Mother In Law Suite?

A mother-in-law suite is essentially a guest house that's meant to house your in-laws. A mother-in-law suite can be a small house or cottage that resembles a small apartment with a kitchenette, bedroom, and bathroom. It is usually separate from the main house, but on the same property to ensure that the married couple would get their privacy. 

In-Law Apartment Design Ideas

Designing the in-law apartment is one of the more exciting aspects of building a backyard unit. During this stage, you have the opportunity to create a home that meets all of your needs.


How the home looks from the outside is completely up to you. Though there would be two separate structures, you don’t want either dwelling to look out of place.

So many homeowners choose the smart design to have a  facade for the in-law apartment that resembles that of the main home. This doesn’t mean the second home has to be a replica. But rather, it can be in the same style or share design elements. For example, the two homes should use a similar color scheme or matching materials. However, if the look of your new backyard home isn’t contingent on the main home, you have many more options available. The parents moving in can decide what architectural style they prefer.

Popular styles for in-law homes include cottage, farmhouse, craftsman, and contemporary.

If the two homes are different styles, you can find ways to ensure that they still coordinate with each other by using a similar color scheme and materials.


Every in-law suite has a kitchen. 

Making considerations like induction and electric stoves with safety measures can help elderly folks stay safe. 

Having two working kitchens in an accessory dwelling unit can be a valuable asset. Not just because of the long term value of having two homes, but also the functionality of two cooking areas for guests, family, and events.  A small-scale kitchen or kitchenette is better than having no kitchen at all when it comes to adding value to your home.

If you ever sell the home or decide to rent out the unit in the future, having a full kitchen creates a more favorable option.

These kitchens don’t have to be large and sprawling. They can take up one wall to save space and still have all the necessary elements, including storage.

Living Room

The living room will provide your in-laws a place to relax in their new tiny home. Including a living room will greatly increase the feeling of them living within their own home rather than feeling like they’re in a spare bedroom.

These rooms don’t have to be large. Depending on the floor plan, the living room may be combined with a dining area and the kitchen. An open plan can help make the smaller home feel and appear larger.

Bedroom Suite

Arguably the most important aspect of the in-law suite is the bedroom. Typically these structures have a single bedroom. The layout and size of these rooms are your decision. However, there will probably be requirements you must meet for this to be a legal living structure. This may include the number of windows, including a closet, and ceiling height.

Choosing the elements of the bathroom has more to do with what the resident will need. For older adults, you may want to include a walk-in shower or a bathtub with low sides. 


Often with age comes mobility issues. Some older adults use canes, walkers, or wheelchairs to get around. Even if your in-laws don’t use these aids, you may still want to consider accessibility.

Features like ramps, wider doorways and hallways, and appliances in close proximity can make living in these homes easier. Use the elements of universal design as a guide of how to include accessibility.

Creating a more accessible home helps aid living independence. Plus, it’s better to have it built into the home rather than trying to retrofit the space to be more accessible.


If you could build your dream home, what would you include? You may want to ask your in-laws to find out what extras they may want in their new tiny home. These bonus features can be anything you can imagine.

Are they into crafting? Maybe add a small room dedicated to their art. Or perhaps they want a place to sit quietly and work; try an office or library.

You may also want to include a porch they can sit and relax on or a garden they can tend to. Incorporate their hobbies and passions to make this new space truly feel like home.


Are mother-in-law suites common?

While mother-in-law suites aren’t overly common, they are significantly growing in popularity — as of 2020, there were at least 1.4 million mother-in-law suites in the U.S.

Over the past few years, cities and states experiencing great population increases have seen a boom in mother-in-law suite construction,4 coinciding with the growing popularity of multigenerational housing.

The construction boom is also the direct result of states and cities pursuing ways to build more housing. In 2017, several California laws streamlined mother-in-law construction permits, resulting in a massive surge in permits and suites.

What Do People Do With A Mother In Law Suite?

The tradition of having multigenerational housing isn’t as common as it once was. While some still practice the age-old tradition of having parents live on their property, assuming that it’s the norm isn’t a smart idea. 

The more common use for a mother in law suite is as a rental property on their home property, like what one may do for an Airbnb. Of course, if people don’t want to rent their in-law suites, they can always use it as a guest house, a place for housekeepers to stay, or an apartment for a teenager in need of personal space.

Find space around your home, or create it

Assess your home to determine the best possible space for the in-law suite. By repurposing existing rooms or rearranging a floorplan, these five ideas fit a suite into a home’s current square footage:

  • The garage or a porch that can be enclosed and transformed into living space are two possibilities, says Patterson.
  • Basements can be made liveable if they have adequate outside egress.
  • Combining two bedrooms to create a suite is another possibility. Buckner says that homes with four bedrooms transformed into two suites, one guest room, and an office are efficient, sellable, marketable, and desired in the Pacific Northwest, where she lives and works. “In a three-bedroom house, reducing the home to two suites by combining two bedrooms is also very sellable and pleasurable to live in,” she says.
  • Underused first-floor living space such as a formal living room or dining room can be replaced or eliminated, Gibbs suggests.
  • An upper floor or a bonus room over the garage can become an in-law suite, though an elevator or chairlift might be needed.

If there’s not enough room in the existing footprint of the home, an addition can create a new master suite. Usually, the homeowners move into the new addition and remodel or upgrade their original suite for their parents or grandparents, says Buckner. Another possibility is to convert the third bay of a garage into a separate apartment-type living space with its own access. “This encourages privacy and autonomy,” she says, “and can be rented to someone else in the event of a vacancy.”


RELATED: All You Need to Know About Granny Pods

More and more homeowners are converting their houses into multigenerational homes for themselves, their children, and their aging parents. Howard Brickman, an old friend of the Bob Vila show who specializes in hardwood flooring installations, added space to his Norwell, MA, home to make room for his mother-in-law, who wanted to move closer to family. Brickman also wanted to be able to help her if she needed it. The walls and floor of the addition were built of energy-efficient Reddi-Form insulated concrete forms (ICFs). ICFs work like building blocks to make light work of foundations and walls. These forms are designed to use less concrete and still carry the load of a soaring 20-foot-gable end wall. Once the shell has been poured, a specialized framing system for the deck or interior floors of the home is set in place for the concrete pour. This high-efficiency, thermally smart home also has a solar roof to help reduce the family’s utility bills and usage. Air quality is a top priority, so all steps were taken to dry the house completely and stop mold from starting once the walls were put up. A deck, beautiful windows, flooring, a fireplace faced in stone, doors, and worry-free trim complete this new, multigenerational home.

Should I build a mother-in-law suite?

Right for you if you want to…Wrong for you if you don’t want to…
✅ Arrange housing for loved ones❌ Pay for new construction
✅ Collect rental income❌ Deal with complicated zoning regulations
✅ Increase your home’s value❌ Pay higher property taxes

» In the market for a new home with a mother-in-law suite? Our friends at Clever can help answer all of your real estate questions and help you find the right agent!

Building a mother-in-law suite

Large and detached mother-in-law suites can cost $60,000–300,000, while additions or conversions can cost $15,000–175,000.

Prefabricated homes are typically built and assembled off-site in a factory, then installed onto a property. This method can be cheaper (and greener!) than conventional home construction.

Adding a mother-in-law suite involves more than the construction itself. The process often involves:

  • Paperwork and applications for site and zoning permits
  • Site preparation before construction
  • Connecting utilities during and after construction

» MORE: How Long Does it Take to Build a House from Start to Finish?

🤔 Other considerations for building a mother-in-law suite

State or local zoning laws may require the mother-in-law suite to be occupied by a family member, meaning you can’t rent it out. Other regulations may make getting a permit difficult — or ban this type of housing altogether.

If you’re part of an HOA, you might need to pay fees to build an addition. Some HOAs even have their own restrictions on the size or type of new construction.

Can I build a mother in law suite in my backyard?

If you don’t already have an ideal space for a mother-in-law suite, you can build one yourself. However, like most major renovations or home additions, be prepared to have to cut through a lot of red tape. 

Before building a mother in law suite, you must check with your city for any zoning laws or permits you’ll need. For instance, some zoning laws don’t allow for mother-in-law suites, requiring you to petition to have your home rezoned or get a variance. This means you may have to collect signatures from neighbors, petition the local planning board, not to mention a variance could cost you up to $500.

If luckily your zoning laws do allow for mother-in-law suites, they may still limit what you’re able to build or include in the dwelling. There may be limits on the height or size of the structure, what the in-law suite can be used for, or some laws ban full kitchens because of the risk of fire. 

What does building an in law suite cost?

Depending on your needs and desired amenities, costs to build a mother in law suite run the gamut. On average, however, the cost to build a new, detached mother-in-suite will cost you around $180,833. Adding an attached mother-in-law suite will save you a bit, as the average cost to build will run you around $154,400.

If you decide to convert your basement into a mother-in-law suite, your costs could be even higher with an average of $185,833. While if you decide to convert your garage, on average your costs will be around $142,000. 

Of course, many factors are in play when calculating your costs. Take into account size, state of disrepair, and amenities. But generally, repurposing an existing space like an attic or garage will be more affordable than constructing an entirely new abode.

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