How Do I Design a Roll-In Shower for My ADU?

By Buz Artiano, BuildX | November 2025

Watching someone demolish a brand-new $70,000 bathroom so they can add accessibility features makes you seriously consider planning ahead. They had just finished the drywall when they had to get out the sawzall. We've seen this happen too many times, and every single time, it could have been prevented.

At BuildX, we build accessible ADUs all over Massachusetts. After building dozens of them that all come with zero-threshold showers, we learned that the difference between planning ahead to add accessibility features and having to go back and do it later is thousands of dollars. But just as importantly, it makes a big difference when your bathroom feels like home and not a "medical facility."

It's very simple, we future-proof your bathroom so when you walk in it doesn't feel like an ADA bathroom, it just has a nice homey feel.

Building accessible from the start saves so much money and hassle over doing it later. The $70,000 bathroom mistake is a real thing, and it can be avoided with smart planning from the very beginning.

Why Does Early Planning Matter for Roll-In Showers?

The math is going to speak for itself here. A curbless shower base adds about $800 when it's installed during construction. But for the exact same thing if you have to go back and add it later is around $4,500. Also, wider door frames cost $150 to put in before the walls are closed up, but widening them after the fact runs $2,200 or more.

Here is what we see when families try to retrofit:

Total savings by building accessible from day one: over $13,000 on just those things on the list. And none of that accounts for the headache of living in a home where a bathroom construction project is going on.

What Are the Essential Dimensions?

Getting the dimensions right is a big deal, it makes the difference between a shower that meets code bare minimum requirements and one that truly works for real people with real needs.

The 36"x36" minimum technically meets code, but it's not truly practical for any kind of caregiving. When someone needs assistance, you really need that extra space. We add a designated 60"x60" space in all our accessible bathroom plans.

What Type of Shower Unit Works Best?

We only install one kind of shower. It is a one-piece acrylic shower made by Barrier Free in New York. They cost about $3,000 delivered, and they are worth every penny.

The build quality is what makes them different. The entire shower is one piece of heavy-duty acrylic with pre-installed grab bars. The threshold is only about five-eighths of an inch, so you can just roll right in. And since it's 38 inches deep, there is plenty of room to move around.

Behind the acrylic, each unit comes with marine plywood backing all the way around. So wherever you might want to add a grab bar later, there is solid wood to screw into. No looking for studs, and none of those awful toggle bolts into drywall.

When we install these units, we coat the floor underneath with waterproofing, then set the shower in epoxy and we add sand bags to weigh it down for three days. Once that cures, there is no flex or bed when you get in. These showers will never move.

Key features we specify:

• One-piece acrylic construction, we never use vinyl
• Integrated grab bars
• Fold-down seat made of teak and steel
• Dual shower head system (wall mount plus handheld on adjustable rod)
• Marine plywood backing for future modifications
• Low threshold (five-eighths inch) for easy roll-in access

Should I Use a Shower Door or Curtain?

For accessible bathrooms, we actually recommend shower curtains over glass doors. Some people are surprised by this, but it's for a good reason.

No matter how carefully we design a shower door, at some point it ends up in the way for someone with mobility issues. A curtain easily pushes aside. When you add a vinyl foam dam at the threshold, you'll have no water leaking.

The foam dam has a sticky back and is about an inch tall. It is very flexible, you just roll right over it, but it's rigid enough to keep water inside the shower. If it wears out, all you have to do is peel it up and stick down a new one. Couldn't be easier.

An important thing to know is that we also mount the curtain rod securely to the walls. We never use a spring tension rod. We believe in overkill when it comes to ADA features, we want our installations to be bulletproof. Nobody wants a shower curtain falling down, and those spring-loaded rods will fail on you eventually.

How Do We Handle Grab Bar Installation?

Grab bars only work if they are anchored into something solid. A toggle bolt that goes into the drywall will fail and tear out when someone needs it the most, and at that point it's too late. Adults don't bounce back quite as easily as they used to.

So we reinforce all the bathroom walls during construction. We install two-by-eight or two-by-ten lumber laid flat in a run at 32 to 36 inches high. That way there's solid backing everywhere, not just where studs are.

Doing this only costs around $200 in materials if it's done during construction. The same setup later, once walls are finished and closed up, will be $1,800 or more because you have to open the walls back up and re-tile.

Placement matters as much as installation quality. We don't ask you where you want grab bars because most people don't know until they actually need to use them. Instead, we come and watch how a person actually uses their home on a day to day basis. We ask you to walk in and out of the shower a few times while we watch where your hand naturally reaches out and that's where we put the grab bar.

Maybe that means we need to put horizontal bars, or vertical, or even L-shaped. The right setup depends on the individual, it's not standard.

What Makes Roll-In Showers Look Luxe Instead of Institutional?

Just because it's accessible doesn't mean it has to look medical. We borrow from high-end hotel design to make accessibility invisible:

• Linear drains at the wall create seamless floors without visible drain covers in the middle of the shower floor
• Decorative grab bars that look just like towel bars and blend right into the design
• Textured porcelain or stone give you slip resistance without looking like a hospital
• Floating vanities offer knee clearance for seated users while appearing very modern
• Handheld showers on stylish slide bars serve dual purposes without screaming accessibility
• Recessed niches at multiple heights ensure everyone can reach toiletries regardless of whether they are standing or seated

The finish options on our one-piece units include smooth surfaces and tile-look textures. Both of these surfaces clean easily and will last forever.

Is a Roll-In Shower Right for Every ADU?

Not every project needs a full roll-in shower setup. If you're building a rental unit for young professionals with no accessibility requirements needed, a standard shower makes more sense. The $2,000 to $3,500 investment in accessibility features needs to match what you will be using the space for.

That said, we usually don't recommend skipping all of the accessibility planning. Even if you don't need a curbless shower today, putting in the wall blocking costs almost nothing. Maintaining 36-inch doorways throughout is also just convenient design. These decisions leave your options open for the future without committing you to specific features right now.

The question is whether you want to spend $2,500 now or face a potential $70,000 project later. For most people who are building an ADU for aging family members or for their own future use, the numbers definitely say you should build accessible from the start.

Ready to Plan Your Accessible ADU Bathroom?

The difference between a bathroom that works for someone of any age and one that requires expensive additions later is all in your planning. Wall blocking costs $200 now or $1,800 later. A curbless shower adds $800 during construction or $4,500 after the fact.

If you are exploring ADU options for yourself or a family member, download our Accessible ADU Planning Checklist to ensure your project includes the features that matter most for long-term livability.

When you are ready to discuss your specific situation, schedule a consultation with BuildX. We will walk through your property, understand your accessibility goals, and show you exactly how to build a bathroom that works for decades without looking like it belongs in a medical facility.