More and more Americans today are opting toward living in multi-generation homes. The reasons for this can be many — changing societal norms, high living costs, or simply individuals wanting to stay close to their older parents. So, in order to accommodate two or more generations in the same house, couples prefer a private, separate unit for their aging mom and dad. And this is where a mother-in-law suite comes in — a far better alternative to using a spare bedroom — which families used to do earlier. Now, let’s see what it means in detail.

What is a mother-in-law suite?

A mother-in-law — also called a granny flat or accessory dwelling unit (ADU) — can be an individual or attached unit — built on the same property. It is designed so as to offer privacy and independence to aging family members. You can construct it as a separate addition to your house or simply customize a garage, basement, or guest house to convert it into an in-law suite. It usually features a bedroom and full bath as the minimum requirements. But you can also add extra rooms such as a sitting room or a small kitchen.

How Much does it cost to build a mother-in-law suite?

If you decide to get this separate living space for your property, the first concern is to get your budget right. Now, your budget depends on accurately estimating the cost of a mother-in-law suite addition — which takes into account various aspects. The most notable factors are the scope of the project, labor and material charges in the vicinity, equity built over the years, etc. Your involved costs also vary a lot based on your zip code and the size of your project. For example, in Los Angeles, a small in-law suite addition can cost around $15000, whereas a large in-law suite addition can go as high as $40000. Yes, it varies a great deal, based on your inputs. But this is how you get an accurate number.

Now that you have arrived at your budget, let’s help you with some simple tips to get started. So, here we go!

Simple tips to build an in-law suite

Check if your area code allows a separate add-on

The first important step is to check your building area codes because most norms don’t allow further additions to your home — apart from a bedroom, bath, sitting area, and kitchen. If you simply convert a part of your property into a MIL suite, it should not be an issue. But adding a kitchen and building a free-standing dwelling will require you to seek separate permits

Decide on the space and location

Depending on whether you wish to add or renovate, look for that perfect spot in your home. Do you want to transform your garage, porch, or backyard into an enclosed room? What about your guestroom? If it’s seldom used, you can convert it into an in-law suite.

Again, if you wish to create a new room altogether, maybe you can choose an area on the ground floor — located next to a bathroom. Whatever you do, keep in mind that your aging parents should have a comfortable space with a lounge, bed, and bath. As for the kitchen and dining room, easy access to both is sufficient. Of course, if you have the luxury, you can add them into her dwelling as well.

Read more: Home Renovation Options For Aging Parents

Check your septic permit

This is again important. Usually, septic tank permissions allow connections up to three bathrooms. You might need additional permissions if you have to increase the capacity of your tank to cater to more baths.

Keep power connections separate

It is recommended to keep separate sources for the power, A/C, and heat. This step shall keep you prepared for the future if you wish to rent out the suite to someone in the coming years. Moreover, doing so will allow you to shut down the unit when it is not being used.

Finally, note who will be living in the in-law suite

Before planning the layout of your mother-in-law suite, consider who will live there. Depending on the inhabitants’ needs and preferences, you might need to consider the type of bathroom layouts (assisted baths or no-slip floors), the width of hallways and doors, privacy and independence levels, etc. It all depends on your cohesive decisions.


A mother-in-law suite is certainly a desirable feature in your home that can serve multiple purposes. Apart from your parents using it, you can also utilize it as a home office, guest quarters, future residence for your grown-up kids, or rental apartment. Moreover, this multi-functional dwelling also increases the ROI value of your property in the real estate market. Why? Because an attractive add-on always seems more appealing to buyers. Therefore, overall, it is a wise investment decision and you can go ahead with it. No Questions Asked!

Building A Mother-In-Law Suite? Check Out These 5 Simple Tips was last modified: May 23rd, 2022 by Anisha Dutta
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It is incredible the number of people you can find underestimating the money that it will be necessary to make additions to a property. You may think with only the money enough to make walls, pipes, and electricity, etc you can do it. But if you live in an old house, if you find something against the rules, you have to spend money to fix it, so and so, you finish your budget and you end upset. Think a lot before you make an addition.