Wendy and David Tracey are concerned.

Their son Jacob, who has severe cerebral palsy, is 22 years old. They want him to live at home as they all get older, but preparing the house to better accommodate their needs has been difficult and frustrating.

Luckily, the Traceys own a rancher. Single-floor living will help as Jacob and his parents age.

Even so, seemingly normal design details become flaws, and they are magnified every day. A single step down from the back door to the patio is a challenge for Jacob's wheelchair - and the person assisting him. Jacob also needs help bathing, and his parents must lift him in and out of the tub - something they won't always be able to do. Plenty of other things would help, too: automatic door openers, low-inclined ramps and wider doorways.

"We want him to live his whole life there," said Wendy Tracey, 41, a Hampstead resident. "We have two other children, and we don't want them to have to care for him when we're gone. We'd like to set it up for him and one or two others who would live there and help him."

The Traceys are not alone in their worries about growing older and coping with medical issues while trying to live in a house designed for young, healthy residents.

To help tackle these challenges, the National Association of Home Builders Research Center is opening its LifeWise Home in Bowie next month. The prototype house, under planning and construction for two years, is meant to be an idea factory for builders and homeowners as they plan homes that will adapt to an aging population.

The 1,900-square-foot house, designed by La Plata-based architect Lisa Holmes, incorporates a concept called universal design, which aims to accommodate its owners throughout their lives. The home will be sold in about a year with pricing expected in the mid-$200,000 range.

"It's wise for everyone to consider these things now," said Andrew Kochera, senior policy adviser at AARP in Washington. "Universal design is attractive to everyone - from the young mother dealing with a stroller and groceries, to elderly people."

AARP, formerly named the American Association of Retired Persons, says that by 2020 those ages 65 and over will spike to 53.7 million from the current 34.8 million. Survey after survey has shown that most older Americans want to live at home, but those homes often lack the amenities they will need.

"Most older people live in the same home for up to 40 years. That means you have 20- to 40-year-old homes that were designed for the Cleaver family; not for the elderly," said Ilene Rosenthal, director of the Maryland Office on Aging.

Layout

The LifeWise house includes designs and amenities that were priorities among older Americans surveyed by the research center and Harvard University's Joint Center for Housing Studies.

Among the top requests of those surveyed: storage, one-floor living, security, convenience and safety.

All of the first-floor LifeWise rooms, doorways, closets and hallways are large enough for walkers and wheelchairs. The main bathroom, often an obstacle course for seniors, has a dual entry that serves the living area and the first-floor, master bedroom. Roll-under vanities, a roll-in shower and a whirlpool bath are included. Grab bars line the shower and toilet spaces.

"The bathroom is the most dangerous place in the home," Rosenthal said. "It's confined, slippery and wet. Older people have a fear of bathing alone. A stall shower is ideal."

Although there is no elevator (they can cost $15,000 or more), the house is designed so one could be installed. The staircase is wide enough for a small chair lift and it has dual railings, lower steps and wider stair treads for easier climbing.

Upstairs, a loft with a sitting area and sleeping space is available for a caregiver, children or guests. It contains a kitchenette, bedroom, closet and full bathroom.

Plenty of windows provide natural light. Colors are bright. Darker baseboards contrast with the almond-colored walls to add definition. Darker, maple kitchen counters and tables are edged with an off-white trim, also adding definition.

"When people have cataracts, definition of horizontal and vertical helps," said Charlotte Wade, a senior research analyst with the research center.

Direct lighting in the stairwell, bathrooms and kitchen also helps residents see better.

Appliances also are senior-friendly. They include a stove with front-end, easily reachable knobs, a waist-level microwave space, an elevated dishwasher and a side-by-side refrigerator that is easier to use for those in wheelchairs. Even the water heater has safety in mind. The unit brings in cold water through a pipe, heats it and sends the hot water to the destination sink, on demand. These heaters, which come in gas or electric, start at about $500 at places such as Home Depot.

The water heater, along with other heating, air conditioning and ventilating systems, is on the main floor so homeowners can maintain it without having to go down to the basement.

Security is another feature. Images of visitors at the doorways are caught on camera and displayed on the TV screen. Residents can activate lights and change thermostat settings by voice command through the telephones, which communicate with a central home computer. An intercom system, centered in the kitchen, connects to upstairs rooms, bathrooms and to the main downstairs rooms.

The basement currently is reached by a double-railed staircase. The garage entrance to the home has a ramp for wheelchair accessibility.

Slowly but surely

Several builders are aware of universal design, but many said that, at this point, it is complicated and too expensive for them to offer.

Columbia-based Ryland Homes will modify a home at a customer's request, said Earl Robinson, a spokesman. But Robinson predicts more universal design on the horizon - particularly in Ryland's hometown.

"It's moving radically fast," Robinson said. "By 2010, a tenth of Howard County's residents will be over 65. That clearly increases the active-adult market. We're gearing up."

"Philosophically, many builders are open to the ideas, but they don't know what to offer or how to market it," Kochera said. "The LifeWise house will help promote it to the major trade groups."

Harford County-based Gemcraft Homes is active in senior-oriented design and is building developments in Delaware. First-floor master bedrooms, in-law suites, elevators, enlarged kitchens, smaller lots and family rooms are included in some developments the company is building in Sussex County. The homes cost about $280,000. Gemcraft soon will offer floor plans in Delaware that include elevator rough-ins or full elevator systems as options (for about $20,000).

"They're selling faster than we can build them," said Dale Hevesy, a Gemcraft vice president. "We had 145 lots in one [Delaware] community. We opened the model a year ago and only five homes are left to sell."

Preparing a home now will save money in the future, some builders said.

Pre-wiring for a chair lift or elevator, for example, won't add much to a home's initial cost - and could save money when it's time to install one. And buying a home with a first-floor bedroom now can save thousands in renovation costs later.

"Until they're confronted with a life-changing illness, they're not always thinking about new technology," Rosenthal said. "Over time, this will change, but people are reluctant to invest until they feel there's a need."

The Tracey family knows there will be a need and is deciding now what changes to make to its Hampstead home. Wendy Tracey said it is a challenge to find the features the family will need at reasonable prices. It also is difficult to find builders to make the renovations, she said.

"We are definitely starting the planning process," Wendy Tracey said.

The LifeWise Home at 16218 Pennsbury Drive in Bowie will be open to the public at least once a month. The schedule is not firm yet. Updates will be available at www.nahbrc.org.