What Features Should Every ADU Have That Most Builders Skip?

By Buz Artiano, BuildX | April 2026

Watch: Most ADUs Aren't Built Like This

When you compare bids for an ADU, sometimes the numbers look very close. One company may bid a few thousand dollars less than the others. The floor plans seem alike and the timelines are similar, so you decide to take the lowest bid. When you sign the contract, you think that all the important things will be covered. However, months later you are in your finished ADU and reach for a towel that is in a closet down the hall, or you flip a light switch that isn't there, or maybe the microwave wasn't vented so it blows grease back in your face when you try to use it. These are not just cosmetic complaints. They are daily frustrations that add up over years of living in an ADU that was built to minimum standards instead of a livable one.

My name is Buz Artiano, and I am the founder of BuildX. Our company has constructed dozens of ADUs in the state of Massachusetts, with most of them on the South Shore and Plymouth County. We handle all the design, permitting, and construction under one roof, and that means we supervise every decision from the first visit to the property through the final inspection. That process has given us a clear picture of what makes a livable ADU instead of one that just passes code, including the features that get cut from bids when some builders are just trying to hit a certain number rather than building your home.

We have inspected many finished ADUs built by us and other builders, and we know exactly where corners get cut. We have a list of constant annoyances that comes from building these units over and over and seeing what people actually need once they move in. And this article is that list. If you are comparing different builders or reviewing a bid, these are the things to look for and the questions to ask before you sign anything.

What Are the Features Most ADU Builders Leave Out?

The things that get skipped aren't fancy, expensive upgrades, they're just small decisions that a builder either thinks about or doesn't. After building dozens of ADUs, we've noticed a handful of things that almost all builders leave off their estimate. They leave off vented range microwaves, closet lighting, bathroom linen closets, three-foot interior doors, and accessible shower fixtures. None of those things cost more than a small fraction of the cost of the build, and honestly, they're really not optional if you plan to live there for more than a few years.

We're not saying that builders leave things off the list to be purposely deceitful, but most of them are working from a basic residential checklist meant for a full-size house where a linen closet is down the hall and the bedroom closet is big enough that you don't need extra lighting to find things. An ADU is a compact space where rooms have to serve multiple purposes. When a builder uses a house checklist for an ADU floor plan, the details you need in a small space like that get left out.

Why Does a Vented Microwave Matter in an ADU?

In a full-size home kitchen, a range hood deals with the grease, steam, and smells. In a small kitchen like in an ADU, the microwave mounts above the stove and works as your vent system too. But that only works if the microwave is actually vented to the outside. When it's not, the fan just pulls air in and blows it right back into the kitchen, it essentially does nothing but move all the air around inside.

A recirculating microwave moves air around but doesn't vent it out of the kitchen. In an ADU with 450 to 900 square feet of living area, that means cooking odors and grease particles are all added to that small space. After a while it starts affecting your air quality and it can ruin your cabinets. It's a very simple thing to fix during construction. We just run a vent duct from the microwave to an outside wall. The cost difference between a vented and unvented installation is next to nothing if you do it during the build. After the walls are closed up, it becomes a renovation situation.

Do Closet Lights Really Make a Difference?

They do, and for some reason they're always getting skipped over in residential construction, not just ADUs. This one is personal for us too.

In an ADU, closets are going to be smaller than in a full-sized home. A normal bedroom closet in an ADU is maybe four to five feet wide. Without a closet light, the only light you have is what comes in from the bedroom. Which means you can't see anything that's more than a foot inside the doorway. For someone who is trying to age in their ADU, messing around in a dark closet can cause a fall. It's really an inconvenience that's completely unnecessary, all you have to do is add a closet light.

The electrical work for a closet light only takes a few minutes to get all the wiring in place and the only cost is for a small light fixture. When a builder doesn't include closet lighting it tells you that they haven't thought about what it will actually be like to live in the ADU.

Why Should Every ADU Have a Linen Closet in the Bathroom?

This is another one we catch all the time on ADU builds.

In a single-family home, the linen closet is usually somewhere in the hallway by the bathroom. In an ADU, there isn't always a hallway there. If there's no storage in the bathroom, then you have to go to your bedroom to get towels, washcloths, and toiletries. This is a failure to create a functional layout, it has nothing to do with design preference.

We design bathroom linen storage into every ADU floor plan because it's the only way it works in such a compact space. In a 900-square-foot unit, every room has a purpose and a function, there's no extra room for hallways or spare closets. When we lay out a bathroom, we make sure there's wall space for a linen cabinet before we finalize where the vanity and shower go. You have to do it in this order because if you place the vanity first and the shower second, the linen storage gets whatever is left, which is usually nothing. We do it the other way around because we've built enough of these to see where people actually reach for things when they live here full time.

What Door Width Should an ADU Have?

Standard inside doors are two feet, six inches (30 inches) wide, which is fine for most people, until it's not. A wheelchair has to have a 32-inch-wide doorway. A walker needs about the same amount. And even if you don't need any of that, a 30-inch door makes it harder to move furniture, carry laundry baskets or groceries.

Every interior door in this ADU is three feet (36 inches) wide.

The cost difference between a 30-inch door and a 36-inch door is only a few dollars per doorway, it's not going to cost you hundreds. While we're in the rough-in stage it's easy to widen the doorframes. But trying to go back and widen the door after the walls are finished requires tearing out the casing, reframing the opening, patching the drywall, and repainting. It turns one doorway into a whole renovation project when it didn't need to be. Add the wider doors during construction, it will pay off later.

What Electrical and Mechanical Features Get Overlooked?

There are two main things that we always include in our ADUs, but we almost never see from other builders. Those things are 200-amp electrical service and an interior-accessible electrical panel.

A 200-amp service is enough to make sure you can run everything in the ADU like the heat pump system, electric cooking, a dryer, and other electronics without ever overloading. We've noticed that a lot of builders will just install a subpanel that gets its power from the main house, which works at first, but you'll be very limited in the future. An interior panel makes it easy to reset a tripped breaker without climbing into a crawlspace or walking outside in winter. For an elderly person, a crawlspace may not be possible for them to navigate.

Massachusetts requires two means of egress for ADUs over 450 square feet, which means a second exterior door. That is a code requirement, not a builder choice. But whether your builder plans the panel location, the service capacity, and the circuit sensitivity around the actual occupant is a design decision that separates a code-minimum build from a livable one.

Is Every ADU Build Missing These Features?

No. There are some builders that include all of this stuff, sometimes they only include some of them. We're not saying that every builder is cutting corners, we're just saying that some of these features are easy to overlook on a bid sheet, and unless you know to ask, you won't know they're missing until you move in.

We include vented microwaves, closet lights, bathroom linen storage, three-foot doors, accessible shower fixtures, and interior panel access in every ADU we build. That's all standard, you don't pay extra for those things, and that's because of all the things we've learned from building so many ADUs. But we are a design-build company on the South Shore of Massachusetts, and our process might not be right for everybody. If your priority is the lowest possible price, a builder working to code minimums will save you some money. If you are building an ADU for a family member to live in for decades, these are the details that determine whether the space works.

Your ADU Checklist Before You Sign a Contract

The things that separate a livable ADU from one that just passes minimum inspection aren't even expensive. They're just decisions that either get made during design or forgotten about after it's too late. Before you sign a contract with any builder, ask whether vented kitchen exhaust, closet lighting, bathroom linen storage, three-foot doors, and accessible fixtures are included. If the answer is no, ask what it would cost to add them. That conversation will tell you more about your builder than a number will.