Finding a home with a mother-in-law suite can be tricky. Many home search sites don't have filters for this feature, and an in-law suite can be called different names, making it difficult to search by keyword. That's why we recommend finding a real estate agent to help you house hunt.
How to find homes with mother-in-law suites
Get help from a local buyer's agent
Working with a buyer's agent is your best bet for finding a home with a mother-in-law suite.
Real estate agents can access the multiple listing service (MLS), a private database with local real estate listings. The MLS contains more accurate and detailed information than public-facing search tools. Agents can search for additional square footage, additional rooms, separate entrances, keywords in the "public remarks" field, and more.
An experienced agent may also already know of local homes for sale with mother-in-law suites. They can accompany you to view the homes and point out unique benefits and potential issues with the suites.
Looking for a home with a mother-in-law suite?
A top local agent can make your search much easier.
Search for a mother-in-law suite on Zillow and other sites
You can try searching for a house with a mother-in-law suite on home-buying sites like Zillow. But it can be a difficult process, since an in-law suite isn't usually listed in the home features.
Most sites, including Zillow, don’t have filters or categories for in-law suites, but some do. For example, Homes.com has a filter called "Interior Spaces" where you can check "In-Law Suite." And Redfin has a "Home features" filter where you can check "Guest house."
If you can't find the right filter on the site you're using, try searching by keyword. You may have to use words besides mother-in-law suite, such as guest house, addition, accessery dwelling unit, and in-law suite.
Check the listing descriptions and floor plans to ensure the houses in the search results actually have in-law suites, since sites often return inaccurate results for this type of search.
What to do before you buy a home with a mother-in-law suite
Make sure the mother-in-law suite (also called an accessory dwelling unit [ADU]) complies with local laws and regulations and is safe to live in. We recommend consulting a real estate attorney, an experienced local realtor, and a home inspector to ensure the suite is in compliance.
Check local laws and regulations
These are the types of documents and ADU regulations you may need to check before buying a house with a mother-in-law suite:
- Zoning compliance: Contact your local zoning department or use online zoning maps provided by your municipality to confirm that the property is zoned for multi-family or accessory dwelling units (ADUs). Ensure that the suite has the necessary zoning permits. You can request documentation from the seller or check with the local zoning office.
- Building code compliance: Contact your local building department to verify that the in-law suite was built with the necessary permits and approved by local building inspectors. Ensure that the suite has a certificate of occupancy, indicating it's safe and habitable.
- Property records: Check the property title and deed for any restrictions prohibiting ADUs.
- Homeowners association (HOA) rules: If the home has a homeowners association, check the bylaws to ensure the HOA permits mother-in-law suites. If you can’t find rules about mother-in-law suites specifically, see if there are rules about guest houses.
- Rental regulations: If you plan to rent out the suite, verify that it complies with local rental laws and obtain any necessary permits.
Get a home inspection
Hire a licensed home inspector to inspect the property, including the in-law suite. The inspector will check for code compliance, safety issues, and overall condition. If the inspector flags potential issues, consider getting additional inspections for specific systems, like electrical and plumbing.
Building a mother-in-law suite vs. buying a house with one
It’s often simpler and less expensive to purchase a home with a mother-in-law suite in good condition than it is to buy a house and then build one.
But if you can't find a house with the type of space you're looking for, it may be worth the cost, time, and effort to build a mother-in-law suite. Make sure you can legally build an ADU on the property before you start planning.
Building an in-law suite generally costs $40,000–130,000.[1] The fees include design and planning, city fees, construction labor and materials, and finish materials.[2]
But costs vary widely depending on your location, the size of the suite, and whether you're converting an existing space or building a separate structure. For example, converting a finished room may cost as little as $10,300,[1] while a new construction build of about 500 square feet may cost as high as $216,500.[2] You'll also need to plan for ongoing expenses, like utilities and insurance.
Construction will likely take several months: about 2 months for converting a space and 4–5 months for building a new structure. You won't be able to start building until you get permitting, which could take 1–2 months.[1]
For more information on costs, types of builds, and financing, read our guide on mother-in-law suites.
What is a mother-in-law suite?
Mother-in-law suites — also known as multigenerational suites, secondary suites, granny flats, and accessory dwelling units (ADUs) — are additional living spaces on the same property as a single-family home.
In-law suites can be a converted space within the primary residence, such as a garage, basement, or attic, or a separate structure detached from the main house. They typically feature at least a bedroom and a full bathroom. Many also include a living room and a kitchen or kitchenette and their own entrance.
People often use mother-in-law suites as housing for relatives, rental units, or home offices.
