What is an in-law suite? It's the most common name for a small dwelling on the same property as (and perhaps attached to) a single-family home, where an aging family member (or others) can live with some modicum of privacy and independence. It's often a separate space with its own bathroom, sometimes in a basement or over a garage.
In-law suites are also referred to as accessory dwelling units, multigenerational units, secondary suites, or granny flats. In Hawaii, they're known as ohana units. In the Southwest, they're frequently called casitas.
No matter what the name, they're a desirable feature in a home that comes in handy in many ways well beyond providing a place for mom alone. Here's everything homeowners need to know.
What is an in-law suite?
The traditional in-law suite can be either connected to the main dwelling of the home (perhaps in the basement), or an external, separate structure, like a small cottage on the property or a converted garage. Minimally, an in-law suite has a bedroom and full bathroom. It can also come with additional rooms, such as a sitting room or a small kitchen.
Alternate uses for separate suites
When not in use by an aging parent, an in-law suite can serve many purposes, making it a wise investment. Here are some uses to consider:
- Home office: "More and more buyers are looking for a place to work from home," says Mike Dinella, broker salesperson with Lenny, Vermaat & Leonard Inc., Realtors® in Haddonfield, NJ. "So this area could be the perfect spot for your small business."
- Guest quarters: When out-of-town guests come to visit, an in-law suite is the perfect place to give them a little privacy, with their own bedroom and bathroom.
- Residence for an older child: Adult children who may need to live at home while establishing themselves financially can use the space as an apartment, perhaps even paying a little rent.
- Short- of long-term rental apartment: Since many in-law suites are fully equipped apartments, they make ideal rental apartments, which can bring in added income from long-term renters or short-term rentals on Airbnb.
What's the cost of an in-law apartment?
The cost to add this amenity to your home varies widely, depending on the size, details, and whether it will be an addition to an existing home or a stand-alone structure. When adding an in-law suite to an existing home, expect to spend an average of $32,700 to $63,000. If you're building a new structure, it can cost as much as $125,000.
In-law apartments as a sales feature
Thanks to their versatility, in-law suites are an attractive feature to look for when buying a home—or to play up in your home if you're selling.
"A mother-in-law space, or even the potential for one, can make your home more desirable to buyers," says Dinella. "With multigenerational living on the rise, buyers are frustrated that they can’t find a home that meets their needs. There are limited choices, so they start looking at homes that can be easily modified into a residence with a mother-in-law apartment. If I have a listing with a first-floor bedroom and full bath, I’ve been advertising it as a 'potential multi-generational suite.' It creates a lot more buyer traffic."
The best advice Dinella has for homeowners who feel the need to add a space for aging in place to their existing home is to configure it with an open floor plan.
"An open floor plan has versatile uses after the fact. It's easier for buyers to envision the space as something else if they don't need to use it for its original intention," he says.
Are in-law suites legal?
Local ordinances vary when it comes to the amenities of an in-law suite and its use. To find the laws specific to your property, go to the zoning office with your lot and block number, to find out if having such a suite on your property is permitted.
If zoning laws do not allow an in-law apartment, it may be possible to get a variance.
"You may have to send out certified letters to the neighbors and get their signatures," says Dinella. "The cost of a variance could run up to $500."
You will also need to obtain building permits. Even then, there may still be limitations on what the suite can include or how it may be used. Some zoning laws do not allow full kitchens, because of the risk of stove fires. Some laws do not allow such suites to be rented out if they are no longer being used for an older relative.
Bottom line: Know the local laws before investing in a home with this amenity, if you are hoping that it may become a money maker.
Despite a few negatives, homeowners find the pros outweigh the cons, and that in-law suites are a smart investment both while they are living in the home and when they go to sell.