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House with an ADU (in-law suite)

The collection of house plans below include floor plans with an ADU (in-law suite, aka mortgage helper).

About In-Law Suites

I recently had the opportunity to visit my boss at her new home. It is gorgeous and while sitting by the pool, I noticed there is a separate, smaller house beyond the pool in her backyard. I inquired as to what the building was used for and she informed me that it is an in-law suite. She and her husband do not use it and we joked that I could move into it because her property is so pretty. Her husband’s mom lives in another state and stays in the main house when she comes to visit and my boss’ mom passed away years ago. I was intrigued by the idea of an in-law suite as it would be so convenient when I, or fellow grandparents, visit their grandchildren or need to help out the parents for a period of time. I researched in-law suites so I could learn more about them.

Related: Types of In-Law Suites | Worth building an in-law suite?

What is an In-law Suite?

An in-law suite, sometimes also referred to as a mother-in-law suite, casitas, a granny flat, a secondary suite, a multigenerational unit, or as in Hawaii, an ohana unit, is a small house or another dwelling on the same property as a single-family home. This type of extra unit on a property can be used for an older family member who needs care or a family member or other person who is coming to help out with the children or other tasks around the house to move the family forward in their goals. It can be a separate space or it can be a room inside the main house that has its own bathroom and is located possibly in a basement or even over the top of a garage.

No matter what name you use to refer to an in-law suite, the unit and concept are becoming more and more popular in today’s busy world’s parents. Many parents need more help than ever before while juggling careers, children and their activities, along with other goals and pursuits. Many younger couples, when searching for a home to purchase, now consider an in-law suite a non-negotiable in one of the features they want in a house. They preferably want something that allows the family member that is coming to live with them their own space, including a bathroom, and it is even better if it has its own kitchen or kitchenette.

How Much Does an In-Law Suite Cost?

For families who want to add an in-law suite to an existing property, the cost for this popular amenity can vary quite a bit, depending on the size of the structure, the features of it, and whether it will be an addition to the home that has to be constructed as a standalone structure, or if it will involve renovating an already existing area of the home. One might expect to spend an average of around $32,000 to $63,000 if simply renovating an area of the home to turn it into an in-law suite and if you decide to build a completely new structure for your in-law suite, you can spend up to as much as $125,000, depending on what features you want to implement into the suite.

Future Selling Feature

The fun part about adding an in-law suite to your existing home is that should you decide to sell it in the future, it then becomes a great selling feature for your house. Many families need this extra space as an in-law suite or since it is very versatile, it cant be used for some other reason. Either way, it will definitely help you sell your home for a much higher price since it adds a lot of value to your home.

Other Uses for an In-Law Suite

As in the case with my boss, their separate structure that was meant to be an in-law suite is now being renovated as an office area which many families choose to do when not using the suite for in-laws or other family members. It can also be used as simply a guest room for family and friends who need to stay over or as a separate residence for an older child who wants their own space but is not quite ready to leave the nest.

An in-law suite is a great way to accommodate grandparents or others who come to help out with expenses, child care, or other reasons while maintaining the privacy of each family member. They are a great way for a family to live together on the same property but not have to be together too much overall.