HACKENSACK, N.J. — When designer Marlene Wangenheim was called in to renovate a master bath, her client was looking to make the space beautiful and comfortable.

But Wangenheim, of Interiors by Design in Morristown, thought the 50-something client should think about the long term and what she might need as she aged.

The result is an expansive, three-room luxury renovation but with a secret: It can accommodate a person who uses a wheelchair or walker. Design choices such as low shelves, an oversized shower and wider doorways mean that the homeowner can keep using the room even if she loses mobility.

This kind of accessible design is expected to become more popular as the giant baby boomer generation ages. Experts say even small design choices can help people stay in their homes in their later years — which, according to polls, most want to do. And, as in the Kinnelon bathroom, the accommodations don’t have to be obvious or look institutional.

One obstacle to the use of accessible design, however, is that a lot of homeowners resist the idea that they might become disabled. Often, they’ll say, “There’s nothing wrong with me; I don’t need a grab bar.”

Rather than raise the thought of disability, Wangenheim tries a softer approach, saying, “How about we make it so you don’t have to worry if you’re still in the house in 10 or 15 years?” And she paints the design choices as ideas that would make the homeowner comfortable now: for example, rounded edges so they don’t bump into sharp corners if they use the bathroom in the middle of the night.

Stephen Melman, director of economic services at the National Association of Home Builders, agreed that many accessible design choices — such as curbless showers and improved lighting — make homes safer and more comfortable for able-bodied people, too.

“If you’re bathing a young child in the tub, would it be such a bad thing to have a grab bar — and 50 years later, use it yourself?” he asked.

Companies that make these products are increasingly trying to win over customers by making them look less institutional — offering, for example, “designer grab bars” in finishes such as brushed nickel or bronze, with detailing that mimics towel bars.

Maria Stapperfenne, president-elect of the National Kitchen and Bath Association, said that many products that were designed for accessibility have made it into the mainstream — for example, curbless showers, improved kitchen lights and console bathroom vanities with space underneath.

Stapperfenne, manager of Tewksbury Kitchens & Baths in Whitehouse Station, said she avoids using phrases such as “aging in place” when working with customers.

“Our baby boom generation will never admit that we’re getting old,” Stapperfenne said. “It can’t be something that says you’re getting old. It has to be about comfort and convenience. They’re not buying ‘aging in place.’”

Craig Webb, editor in chief of Remodeling magazine, said that while many baby boomers hate the idea they will grow old, they tend to become more realistic about their future needs as they help their parents “and see the challenges they’re having.”

Carol Rose Volpe, a real estate agent with Abbott & Caserta Realtors in Ho-Ho-Kus, works with a number of older clients who are trying to decide whether to move or stay in their homes. She said many homeowners put grab bars in the bathroom or move the washer and dryer upstairs from the basement, so they don’t have to deal with the steps.

“You don’t have to be 80 for that; there are people who have problems with their knees in their 50s,” said Volpe, who is part of Abbott & Caserta’s “Golden Home Experts” team, which has training in seniors’ housing issues from the National Association of Realtors.

Catherine Abbott of Tydale Developers in Ho-Ho-Kus said that she has installed chairlifts, which start around $2,500, and transformed first-floor sunrooms or decks into master suites for elderly people who can no longer handle stairs. But most older homeowners, she said, put off making such renovations until it’s absolutely necessary.

“A lot of the elderly don’t want to spend the money, or maybe they don’t have it,” she said. “It’s costly, but imagine paying for assisted living or a nursing home.”

And designers say you don’t always have to spend a fortune to make a room aging-friendly; most of the choices don’t cost any more than standard versions, Wangenheim said. The Kinnelon bath renovation cost more than $100,000 — but that was because it was a large, high-end project, not because of the accessible elements.

“We didn’t pay more to make the shower curbless, or use levered handles on the sink or countertops with rounded edges instead of pointed,” Wangenheim said.

However, aging-friendly renovations often require more space, which could add to costs. For example, a room must be spacious enough to allow a wheelchair user to turn around.

“In a 5-by-8-foot room, it’s really hard to do a universal design bath,” Wangenheim said.

In the Kinnelon project, Wangenheim made choices that work both as design elements and as practical accommodations for any future disability. For example, the rooms have pocket doors (or in one case, a sliding Japanese shoji door). That means a person in a wheelchair doesn’t have to maneuver around a swinging door. The toilet is higher than usual and in a room large enough to allow a wheelchair user to turn around.

In the main part of the bathroom, Wangenheim didn’t use a traditional medicine cabinet over the sinks, but instead placed storage in low shelves and in an island with drawers — all within reach for a person who couldn’t stand. The shades, shower and TV are all operated by remote control — no reaching.

The shower has no threshold or door, just a path that’s wide and smooth enough for a wheelchair. Inside, a hand-held shower is within reach of a heated seat. The soaking tub nearby includes a cushioned seat so a person with imperfect balance doesn’t have to climb into the tub — instead, the person can sit on the seat and swing one leg in at a time.

There’s even a refrigerator and microwave in the dressing room — convenient now and potentially more useful later, as the homeowner ages.

The homeowner balked at grab bars, but there are supports in the walls so they can be installed later if necessary. The homeowner, who asked not to be identified, said she wouldn’t have thought of all these accommodations but is glad Wangenheim did.

“God willing, I want to be here for a long time,” she said.