Housing remains at the center of the slumping national economy, and the people hit hardest by the ongoing slump face longer waits before they can own their own homes again.

For former home owners who've gone through foreclosure or have done short sales, it's a long road back their own driveways. Recent regulatory changes extended the waiting period for new mortgage loans eligible for sale to Fannie Mae to seven years for many borrowers who have gone through foreclosure. That makes many foreclosure victims ineligible for the best mortgage rates if they are able to secure loans.

Many short-sellers face two-year waits, though sellers who avoid default are immediately eligible for Federal Housing Administration loans. The National Association of Realtors reported that 15% of all July sales were short sales, where the property sold for less than the original mortgage.

Jeff Lisher, managing director for regulatory policy at the National Association of Realtors, says the array of waiting periods at Fannie, Freddie Mac and the Federal Housing Administration puts the brakes on the next run at home ownership for larger numbers of people. Even with the exceptions for "extenuating circumstances" that shorten some of these waits but require additional documentation, the delays come as a surprise for some of them.

"These rules have been around for a long time, but they haven't come up because home values always went up," Lisher said.

These curbs on prime rate borrowing activity are in place largely because the mortgage collapse that led to the recession was due in part to overly optimistic thinking by many mortgage borrowers. However, as the housing collapse continues to ripple throughout the country, larger numbers of people will have longer to wait to rejoin the nation's homeowners, even if they've worked hard to rebuild their credit.

"The basic truth is, it's going to take a couple of years after somebody short sells their home" to get a new mortgage at the lowest possible rate, says Richard Zaretsky, a real estate attorney in West Palm Beach, Fla.

While many home owners are frozen in place by declining home values, the ones who've gone into foreclosure or had to do short sales aren't just folks who bought more house than they could afford during the housing boom of 2004 to 2006. Some lost their houses because they lost jobs. Others were pulled along in the general decline and sold their houses even if they were underwater on the loans.

Recent conflicting data muddy the turbulent waters of the national housing market. July housing starts climbed 1.7% from a year ago, but building permits dropped. According to a July report from RealtyTrac, there are 325,229 properties across the country in some form of foreclosure.

The seven-year wait is the most extreme barrier to re-entry to homeownership in guidelines set out by Fannie and Freddie Mac, mortgage companies overseen by the Federal Housing Finance Agency. Along with the Federal Housing Administration, they back loans with the lowest mortgage rates. In a post-recession period of extra-tight credit, they're vital to securing a decent mortgage rate, and for home buyers who've been through foreclosure or had to do a short sale, such rates are not easy to get.

Rob Kosberg, a mortgage consultant at Choice Mortgage Bank, also in West Palm Beach, points out that the Fannie and Freddie guidelines ensure that borrowers can't use a short sale to take advantage of a declining market and purchase a similar or superior property at a reduced price, but that financing can be done for people who are willing to pay higher interest rates. He said it's likely that anyone doing a short sale will see a 50- to 60-point drop in their credit score within two months of the transaction, even if the rest of their financial lives are in perfect order.

Even people with higher incomes who've taken hard knocks in housing should do a very careful assessment of their total financial picture before they seek another mortgage, says Douglas Robinson, a spokesman for NeighborWorks America, a nonprofit organization created by Congress to work on housing and community-development issues.

"Manage your credit wisely, pristinely, and as that two-year period comes up, you should be able to come up for a prime cost mortgage," he said. "That's what we're telling the hundreds of thousands of people who are coming to NeighborWorks organizations. It's not the end of the world you can certainly become a homeowner again."