What Accessibility Features Should Every ADU Have?

By Buz Artiano, BuildX | June 2026

You have decided to build an ADU for a parent or aging family member, and now you are looking at floor plans, not sure what "accessible" actually means. The word gets used a lot in brochures and on websites of the builders, but no one explains the difference between the features that matter when you first start to build and the ones that you can add later. You don't want to spend $300,000 on an ADU that will need a $40,000 renovation three years from now because nobody thought about where the grab bar should go or how wide the doors needed to be while the walls were still open.

My name is Buz Artiano, and I am the founder of BuildX. We've built dozens of ADU projects across Massachusetts, mostly around the South Shore and Plymouth County areas. We are the only team you need: we do the design, permitting, and construction. So we see every phase of a project from the first site visit up until you move in. We evaluate septic constraints, zoning issues, utility connections and the requirement to get a permit from the city. Accessibility is not an add-on in our process. It is built into the design from the first conversation.

We have built dozens of completed ADU projects across Massachusetts, with concentrated experience on the South Shore and throughout Plymouth County. Every project we take on moves through design, permitting, and construction under one roof, and every one of those projects forces us to navigate real constraints: septic evaluations under Title V, lot coverage limits, and municipal zoning requirements that vary town to town. Accessibility is not an add-on in our process. It is built into the design from the very first time we have a discussion.

After building many of these units for aging family members, we have found six accessibility features that need to be in every ADU, whether the person who will be living in the ADU needs them today or not. Some of these are obvious but other ones are construction decisions that affect things behind the drywall and can't be added later without tearing the walls apart. This article will explain each one, why it is important and what you need to require from any builder you hire.

What Are the Six Accessibility Features Every ADU Needs?

Every ADU that is for an aging family member should have these six features from the start. None of them are just cosmetic upgrades. Each one handles a certain physical safety risk or a future modification that will be costly or impossible to add after construction.

The six features are: a covered entryway that is even with the threshold, 32-inch or 36-inch inside doors, bathroom transfer space between fixtures, structural blocking in every wall for future grab bars to be put in, large windows for natural light, and nine-foot ceilings. We put in all six in every ADU we build for older family members. The total cost to include them during construction is very small but the cost to add them afterward is either inconvenient or too expensive to do.

Why Does a Covered, Flush Entryway Matter So Much?

The entryway is the first accessibility decision in any ADU, and most builders get it wrong. A standard deck or landing typically is an inch or two below the door threshold. That gap looks minor, but it creates two problems. First, anyone using a wheelchair or walker has to navigate that lip every time they enter or exit. Second, if the occupant ever needs a ramp, the deck has to be torn off and rebuilt to bring the surface flush with the door.

We build every ADU entryway so the top of the deck or landing sits even with the bottom of the door. That way, if a ramp is needed later, it will connect directly to the existing surfaces so no demolition or rebuilding is needed. The second requirement is a covered entryway over the threshold because if the decking is level with the door, water can accumulate at the entryway and leak under the floor. A roof or awning over the entry can keep water off the threshold and protect the structurals that connect underneath.

This is the kind of detail that separates an ADU that's only built for right now from one that's built for the next ten years. It costs almost nothing during construction and saves thousands in work later.

How Wide Should Interior Doors Be in an Accessible ADU?

Standard residential inside doors are 28 to 30 inches wide. That works fine unless there is someone who needs a wheelchair, walker, or even a wide medical equipment cart. Then, every narrow doorway becomes a problem that will limit independence.

Every interior door in an accessible ADU should be a minimum of 32 inches wide. 36 inches is better. The cost difference between a 30-inch door and a 36-inch door during new construction is very small because the frame is already open, so the rough opening just gets built wider. But if you need to widen a doorway after the walls are finished you will have to cut into framing, patching drywall, repainting, and possibly rerouting electrical. That means it can cost you $1,500 per door instead of $50.

If you are talking to a builder who gives you a quote for a standard 28-inch door in an ADU for an older person, ask why. There is no good reason to save $50 per opening when the consequence is an ADU that won't work for a wheelchair.

What Does Proper Bathroom Layout Look Like for Accessibility?

The bathroom is where you should plan the most for accessibility, because it's where most falls happen and where it is most dangerous for those with limited mobility. The important measurement is transfer space which is the distance between the toilet, the shower, and any wall obstructions.

A bathroom that's accessible has to have enough room between the toilet and surrounding walls or fixtures for a person with mobility issues to go from one to the other safely. That means enough room to move from a wheelchair or walker onto the toilet, and from the toilet into the shower, without hitting a vanity, a wall, or a door. The shower area has to be big enough to put in a shower bench or a roll-in configuration if it's needed later.

This is a floor plan decision, not a decision about fixtures. If the bathroom is designed too tight during the planning phase, no amount of grab bars or shower seats will fix the basic problem. The space between fixtures has to be right from the beginning.

Why Is Wall Blocking the Most Important Accessibility Feature You Cannot See?

Blocking means that there is a solid wood backing put in horizontally inside the wall during framing, before drywall is put up. It is the most important decision about accessibility in an ADU, because it's invisible once you close up the walls. It gives grab bars, handrails, and support hardware something structural to connect on to.

Without any blocking, a grab bar is put in with toggle bolts screwed into drywall. That feels solid until someone actually falls and grabs it. But then the toggle bolt tears out of the sheetrock, the grab bar comes off the wall, and the person continues falling, now holding a piece of metal that can break an arm as they are falling. This isn't just a guess. It is a pattern that's happened in homes where grab bars were added later on.

We put blocking in every ADU we build, and we do it differently than what is the standard practice. Instead of relying on the standard 16-inch on-center wall studs to land in the right spot for a grab bar, we install two-by-eight or two-by-ten boards laid flat in a continuous horizontal run at 32 to 36 inches high. That continuous run means a grab bar can go anywhere along that wall, not just where a stud happens to be. We install this blocking in bathrooms, hallways, kitchen areas, bedroom walls, and at every entrance. The simple rule is that if you walk into a room and you want to put your hand out to steady yourself, that wall needs blocking.

The cost of blocking when you are framing is just a small amount of what it would cost to open up finished walls to add it later. And the grab bars don't have to be put in right away. We take a Matterport 3D scan of the property during construction, before the drywall goes up, so we have a permanent record of exactly where every piece of blocking is inside every wall. So when a family calls us two years later and says the person who lives in the ADU needs to have grab bars, we pull up the pictures and show them exactly where the blocking is, have the person put their hand where it feels natural, and screw the bar into solid wood. The whole entire installation takes about ten minutes, because the preparation was done during construction.

How Do Natural Light and Ceiling Height Affect Livability?

The last two features are not traditional accessibility parts, but they will directly affect how comfortable an aging person is with living in the ADU long term. An ADU can have perfect door widths, ideal bathroom layout, and blocking in every wall, but if it feels dark and cramped, the occupant won't want to spend time there.

Large windows that bring in natural light are a necessary thing, not a luxury, especially for someone who might be spending most of their day inside the ADU. Natural light can affect your mood, how well you sleep, and your awareness of space. A well-lit unit seems larger and more inviting while a dim unit, no matter what the square footage is, does not seem like a home.

Nine-foot ceilings will do the same thing. Normal eight-foot ceilings in a small house can feel compressed, especially for someone who's lived in a full size house before. Nine-foot ceilings make a 700-square-foot ADU feel physically much bigger without adding any square feet of floor space. The cost of the framing between eight-foot and nine-foot walls during new construction is very small but the difference in how the ADU feels is a lot.

What Should You Ask Any Builder About Accessibility Before Signing?

If you are comparing builders for an ADU that's for an aging family member, there are specific questions that will separate a builder who understands accessibility from one who doesn't treat it as important. So you should ask whether their standard ADU includes blocking throughout all walls or only in the bathroom. Also ask what size interior doors they normally use, and whether the entryway deck or landing is going to be built level with the threshold of the door. Ask them what happens in three years when the person needs grab bars. Make sure you know if the builder keeps a record of where the blocking is, or does the family have to guess.

A builder who can't answer these questions isn't making the design accessible, they are building a standard unit and hoping nobody needs modifications.

Is Every Builder Going to Include These Features?

Not every builder considers ADU accessibility as a standard feature. Some builders offer accessibility features as upgrades or optional packages, and for families where a younger person without any mobility issues will live in the ADU that might work fine. If you are building a rental unit for a healthy adult child, you probably don't need nine-foot ceilings or continuous blocking in every room.

But if the reason you are building this ADU is to keep an aging parent close to family, accessibility should be part of the basic design instead of something that is added on. The features listed here cost very little during construction and get very expensive to add later on. The question is not whether you can afford to include them but if you can afford to leave them out and hope that nothing changes.

Build It Right the First Time, or Pay to Fix It Later?

Every accessibility feature in this article has one thing in common: it's inexpensive during construction and expensive after. A flush entryway, wider doors, proper bathroom spacing, wall blocking, natural light, and taller ceilings are all things that happen on paper and during framing. Once drywall goes up, the option goes away. Build the ADU your family member will need for the next decade, not just the one that looks fine on move-in day.