What Should You Change in Your Main House When You Add an In-Law Apartment?

By Buz Artiano, BuildX | September 2026

Watch: In-Law Apartment Plus Whole-Home Remodel | Client Testimonial

Most families who are planning to build an in-law apartment spend every design meeting talking about the new space. Where it goes, how big it will be, how to build it so your parents can live comfortably. The main house usually gets left out of the planning and conversation. Then the new addition gets all finished and now the property has two more people living there. The kitchen already felt a little cramped with 3 kids, but now it's supposed to accommodate even more people and of course holidays. But you spent the money on the addition. So the cramped kitchen is still exactly that.

My name is Buz Artiano, founder of BuildX. We've built dozens of ADUs, in-law additions, and whole-home remodels all over Massachusetts, but most of our jobs have been on the South Shore and in Plymouth County. We do absolutely everything from design to permitting to construction. In our Massachusetts work, an addition has to go through all the city permitting and adhere to dimensional setbacks and septic capacity long before anyone gets set on any plan. During the design is also where the existing house either gets addressed or ignored.

Greg and Talia Mehra are BuildX clients. We designed and built an attached in-law apartment for Greg's parents at their home in Hanson, Massachusetts, and we remodeled the main house the rest of the family lives in. That house dates to the 1960s. Three kids and a dog live in it. Talia told us at the start exactly what she wanted the house to be like when we were finished. She wanted it to be light and bright and to maximize space, so we designed the whole thing to be exactly that.

We always love to share stories of happy BuildX clients, but we're going to talk about the Mehras' main house for a reason. They were very happy with the outcome, but what is most important is which changes they still use every day, and the fact that the one they now call their favorite is the one they argued with us about before we built it.

What Should You Change First in the Main House?

Start with the rooms the entire household occupies at the same time. An in-law apartment adds people to the property, and they don't just stay in their part of the house. They come over for dinner and holidays and other things. The rooms that get the most traffic are the kitchen and the room next to it, the storage for both places, and the bathroom your kids share. Bedrooms and hallways can wait.

In Hanson, there were five major changes that accomplished what we wanted to accomplish:

• We removed the dividing wall between the kitchen and the dining room
• We installed an island that was bigger than they had originally wanted
• We added a pantry in the design
• We put flooring that was the same all throughout
• We gutted the upstairs bathroom and gave the downstairs bathroom some nice updates

Every one of those things helps more people be able to use the same room at once without getting in each other's way. That's the test you want to run on your own house before the drawings are all set, because most of the things we did were structural, so they have to be designed in from the very beginning, not after construction starts.

Why Does Removing One Wall Change How Your Whole House Feels?

Greg called the original kitchen and dining room "an old 1960s-style cave." The biggest change to the layout of the house was removing the dividing wall between them. Houses drawn in that decade added extra walls to have the cooking separate from the eating and the sitting, which worked back in the day, but it doesn't work now, especially when the household is growing.

What replaced the "cave" is one open and connected space that goes from the kitchen into the living room. The whole family can hang out there all at once, including Greg's parents. And there's tons of light, which is exactly what Talia asked for at the first meeting.

The wall worth looking at in your own house is the one between the room where food gets made and the room where people sit. If those two rooms are both small and separated by drywall, you're in the same position the Mehras were in. We have to figure out if it's a load bearing wall during the design phase because that changes how the opening gets framed and headed, and that needs to be figured out before anybody gets too attached to a specific plan or layout.

Should Your Kitchen Island Be Bigger Than You Planned?

The Mehras wanted "a little smaller island." We recommended the larger one and told them they would be happy with it. Greg's word for the result afterward was "a godsend." Talia says the island is the part of the kitchen she likes most, and Greg actually said it was his favorite thing about the house. It's the one decision in this project where our recommendation ran was not what the owners originally asked for.

We size islands by how many people will be at them at once, not by how much floor area is left over after the cabinets are set. In a house with an in-law apartment attached, the island gets used just as much as the dining table. Talia described three things they use it for. The family sitting down together at breakfast, extra seating when the in-laws and other relatives come over so the dining room is not the only place to sit, and an open counter for prep, cooking, and baking. Greg calls it the gathering point of the house. An island that's only big enough for who lives there now will immediately seem inadequate when the addition is done and the household grows.

So it's not really about how big of an island fits in the room. It's more about how many people will be standing or sitting at its busiest times, and whether two people can work while the rest sit.

Storage Is a Design Decision, Not a Leftover Space

Talia's line about the pantry makes a great point. "They did design a pantry for the kitchen, they were able to kind of fit that in." It was designed in. It wasn't an afterthought for a corner that nobody was using.

Greg put it a little more bluntly. "There's really no excuse for deciding that you don't have enough storage. There's always ways to have enough storage." Here's how that really works. Storage gets located while the plan is still just on a screen, in the depth behind a wall, in the area by the fridge, in the space a doorway swing was wasting. Once the cabinets are ordered, you can't add that stuff anymore.

In a house with an in-law apartment next door, the main kitchen becomes the room where the extended family cooks on holidays. Ask where the pantry is on the drawing before you approve it. A plan that treats storage as whatever space just happens to be leftover is not a good plan.

One Floor Throughout Makes a Busier House Easier to Keep

"The floors in every room are the same, and the house seems easier to clean and maintain with the open concept sort of in the kitchen living room," Talia said. She came back to it later in the same conversation. "I like the ease of cleaning the floors."

Running one flooring through every room removes the transitions, thresholds, and material changes that create a chopped up look and feeling. Your eye sees connected rooms as a single open space, which is the look we wanted when we took out that wall. In a house with three kids, a dog, and family arriving from next door, it also means one cleaning routine instead of a different one in every room.

The Mehras didn't mention the specific flooring they chose, but the important thing is that they used the same flooring throughout the whole place.

Which of Your Bathrooms Needs a Gut, and Which Needs a Facelift?

The two bathrooms in the main house had very different plans as far as remodeling. The upstairs bathroom was completely gutted and re-done. The downstairs bathroom only needed a few updates. Talia said she was "really excited with the way the bathrooms came out," and the detail worth noting is that the tub stayed. Three kids share that bathroom, and in Talia's words, "there's plenty of space, and we haven't had any issues at all."

We gut a room when the layout doesn't work and we refresh or update when the layout is still doing its job. A bathroom that three kids use on the same school morning is a layout problem, and those problems get solved by stripping the room to the studs and rebuilding it. A bathroom that guests use a few times a week is just a finish problem, and you don't need a demo crew for that. That's exactly why we kept the tub. That fixture was doing its job, so it stayed while everything around it changed.

Count the people who use each bathroom at the same time on a weekday morning. That number tells you which room earns a gut and which room only needs paint, fixtures, and a vanity.

When Should You Leave Your Main House Alone?

We build in-law additions and we remodel main houses, so a lot of people expect us to always recommend doing both. But that's not the case, an addition or remodel isn't right for everyone.

If your main rooms already comfortably hold everyone at once, just leave them alone. If the way your household uses the kitchen and the shared bathroom is going to stay the same when a parent moves in next door, leave them alone as well. If the addition is going to use up the entire budget to be built the way it needs to be built, then do the addition and leave the main part of the house alone. Doing nothing to a house that already works is the best outcome of a design conversation.

Let's be upfront about one more thing here. The Mehras say that they wouldn't change anything at this point. Your list will not be the same as their list. The way we get to your list is the conversation Greg described from our first meeting, which is the "hopes and dreams speech" where we ask for your ultimate dream scenario and then we very politely make it more realistic. Main-house scope gets set in that second half.

What Will Your Main House Need to Do Once Everyone Moves In?

The addition gets the attention because it is the new thing. The main house is where the rest of the family keeps living, and its job changes once the addition is finished. Walk your own house and count the rooms that have to hold everyone at once.

For the Mehras, the answer came down to one wall, one island, one pantry, one floor, and two bathrooms handled differently. The list is short because the changes worth making are the ones that decide how many people fit in a room.