Burdensome mortgages, tight credit, consumer debt, stagnant wages — all have contributed in some way to the sluggish housing recovery. Homeowners who would like to sell won't or can't because their homes have lost value, and those who would like to buy or trade up don't have the means.

As the economy and employment opportunities improve, and consumers are once again thinking about their next home, another obstacle threatens to impede home sales and construction: compatibility. Prospective buyers are discovering a shortage of properties that meet their requirements for how they want to live.

Builders and real estate agents alike are looking to millennial first-time homebuyers and downsizing baby boomers to pump some life into the housing market.

The National Association of Home Builders within the past month reported that demand in the 55-plus housing market was "exploding" and that "pent up demand" for home ownership among millennials "is expected to translate into housing growth in the coming years." Yet recent studies have shown that these two buyer segments are more likely to have difficulty finding the type of home they have in mind.

Despite the differences in their ages, or perhaps because of them, millennials and boomers are looking for many of the same things in their next home purchase. A major issue is affordability.

Millennials especially have complained of being priced out of the market. In an interview with Builder magazine, Nick Lehnert, executive director with design firm KTGY Group, says millennials are looking for something simple.

"The first step is that it has to be attainable," Lehnert said. "They have to understand that they can afford it."

NAHB Assistant Vice President of Research Rose Quint echoed those thoughts while speaking on a panel at this year's International Builders Show.

"The growing numbers of first-time buyers will drive down home size in 2015," Quint said. "As younger, first-time buyers, they will demand smaller, more affordable homes."

A study by the Demand Institute of baby boomer's expectations for their next home purchase divides them into two groups: "upsizers," who are looking for a bigger but moderately priced home, and "downsizers," who are looking for a smaller, less expensive property than their current home.

Both boomers and millennials prefer single-level homes and preferably something more contemporary that is easy to clean and maintain. Boomers want them because they are "age friendly," and millennials want them because with their busy, mobile lives they don't have a lot of time to take care of a house.

A 2013 study by NAHB found that, in fact, 57 percent of homeowners say they prefer a single-level home. According to the U.S. Census Bureau's 2013 American Housing Survey, however, of the 569,000 new homes completed in 2013, more than half (305,000) had two stories or more. Of the total existing housing stock, only about a third are single-story homes.

And, as a Washington Post article points out, "Most of those homes don't have the kind of basic 'universal design' features that older residents will need, like extra-wide hallways, no-step entries, living spaces on the ground floor or accessible light switches and door levers ... just 1 percent of housing units in America have all five of these features."

And then there is the issue of location.

Unlike the 55-plus buyers mentioned by the NAHB, most baby boomers are not planning to move to a senior community. They want to be near family and friends. The Demand Institute study finds half foresee moving no more than 30 miles from their current home, and only a third say they will move out of state.

Millennials, meanwhile, say that when they are ready to buy a home, they would prefer to live in the suburbs. Yet, a majority in either group does not want the types of homes that currently make up a large portion of the communities where they now live or hope to live, while they do want better access to services and transportation than found in most suburban communities.

Builders and remodelers have time to respond to these trends, as it may be several years yet before large numbers of boomers and millennials are ready or able to change housing.

"Builders will build whatever demand calls out for," Quint said.

But transforming the nation's housing stock and entire communities will require a lot more.