A new mortgage product is about to hit the market that could make it easier for owners to repair or rebuild homes that have been damaged or destroyed in floods, tornadoes, hurricanes and other natural disasters.

Dubbed the CHOICERenovation loan, it also will allow buyers to purchase older houses that need some work and, therefore, may be more affordable than newer places.

Four out of every five of America’s 137 million single-family properties are at least 20 years old. But the average age of the country’s housing stock is 42, according to the Urban Institute. That means the typical American home was built in 1977.

Houses with some years on them often need upgrading -- a new kitchen with the latest appliances, perhaps, or a remodeled bathroom with new fixtures and plumbing. Maybe a new roof. That’s why older places tend to languish on the market. People prefer to move into houses that are ready for occupancy without having to do too much to them.

The new loan from Freddie Mac will allow adventuresome buyers to roll the costs of necessary improvements into the loan amount. Better yet, they won’t have to do the work until after they move in. And they can act as their own contractors, as long as they demonstrate that they have the ability.

Freddie Mac doesn’t originate mortgages directly. Rather, it keeps the funds flowing for mortgages by buying loans from some 2,000 lenders nationwide, which borrowers deal with directly. And whenever the secondary market company tells lender-clients it will purchase certain loans that meet its criteria, the product usually becomes available to consumers in short order.

Freddie Mac just rolled out the loan earlier this week, so it will be a few more weeks before it becomes available. But when it does, Danny Gardner, Freddie’s senior vice president for single-family affordable lending, expects it to be a big hit because it addresses so many needs. It’s a multifaceted tool for lenders to keep in their arsenal, he said.

Most importantly, perhaps, CHOICERenovation will make the aging housing stock more attractive to first-time buyers. “There’s a fair amount of housing with deferred maintenance,” Gardner said in an interview. Cash-strapped buyers “should be very willing to undertake those issues if they can get houses at an affordable price.”

Because it can be used as a no-cash-out refinancing tool, the loan also targets current owners who are looking to stay put but need to remodel, seniors who need to renovate so they can age in place, and families who need to redo their places to accommodate aging relatives.

Similar mortgages are available through the Federal Housing Administration, the government agency that insures mortgages on behalf of lenders, and through Fannie Mae, Freddie Mac’s chief rival in the after-market. Both Freddie and Fannie pool the loans they buy into securities and sell them to investors worldwide.

One advantage of this type of loan is that it allows borrowers to finance both the purchase price and the renovation costs all in one loan and with just one closing. When two separate loans are involved, there also are two closings, which can be expensive, depending on where the property is located.

According to the latest data from ClosingCorp, settlement fees range from nearly 5 percent in Pennsylvania to less than 1 percent in Nebraska. The fees are based on the sales price and tax rates imposed by local jurisdictions, and include property taxes, title insurance, appraisals, recording fees, land surveys and transfer taxes.

Affordability and a shrinking inventory of houses for sale are probably the two biggest hurdles today’s buyers must overcome. As a result, there has been a huge surge in the renovation sector. Rookies have been forced to choose between buying houses that need some rehabbing or remaining renters, and potential move-up or move-down buyers have decided to stay put and improve their places rather than settle for something that doesn’t meet their needs and desires.

Since the Great Recession ended in 2009, the renovation market has more than doubled. According to the Joint Center for Housing Studies at Harvard University, the home improvement and repairs sector is now a $400 billion industry.

But what really sets the Freddie Mac offering apart is that it allows people to repair homes damaged in a natural disaster -- or better yet, prepare them for future disasters. Borrowers can use the proceeds on such items as surge barriers, foundation retrofitting for earthquakes, or retaining walls.

If a property has already sustained damage, its owner can use the loan to rebuild it so that it complies with all current applicable state and local laws, including zoning requirements.

Thousands of homes are lost every year to disaster, thousands more are lost to obsolescence, and even more could be upgraded to better survive a disaster.

Eligible properties for the new loan include manufactured houses as well as site-built, single-family houses. However, Freddie won’t deal with lenders that cannot exhibit some expertise in rehab lending.

In most real estate transactions, the focus is on the purchaser and whether he or she can afford to buy the property. But there is another, equally important question: Can the seller afford to sell?

Many sellers become riveted on the gross selling price, and fail to consider how much money they need to net in order to move to their next residence. And that can be a serious mistake, especially if they haven’t built up much equity in their current homes.

The commission they are paying the listing agent is sometimes overlooked, as is the share of their buyer’s closing costs they’ll be expected to pay, what they owe on their current mortgage, and the costs of the actual move.

If the seller doesn’t take those and other costs into consideration, his or her agent should, says Margaret Rome, the broker-owner at HomeRome Realty in Baltimore. It’s part of the agent’s job.

“What the seller needs has no bearing on the price. It is the place to start the discussion,” Rome posted recently on real estate site ActiveRain. “It is a must to find out (the seller’s) expected dollar amount. If no one has explained the cost of selling, or they don’t understand the fees, even with a full-price offer, (the seller) may not be able to afford to sell.”

Her advice to colleagues: “Never price a home without knowing what is owed and what the owners need to move forward. Find out the bottom line, their in-their-pocket number.”

More than a handful of deals have fallen through because a seller didn’t do the math -- or an agent didn’t urge them to.

“It amazes me how many sellers are surprised by all the additional costs,” said Endre Barath of Berkshire Hathaway Home Services in Beverly Hills, California.

Carol Williams of Wenatchee, Washington, once inherited a listing in which she figured out that if the owners did move forward, “they would probably be left homeless.” The sellers’ credit was in bad shape and they had hardly any equity. Fortunately, at her suggestion, they spoke with a lender and discovered the harsh reality of their situation. “They took the home off the market and stayed put,” she said.

According to a recent analysis from Zillow and Thumbtack, a home improvement marketplace, the typical owner will shell out $20,851, mostly in taxes and commissions, to sell their place.

Here’s a brief rundown of some of the costs of selling:

-- Prep work. Window-washing, painting, landscaping, repairs, staging to make the house more presentable -- none of these will add much, if anything, to your home’s value, but they should help sell the place more quickly.

-- Payoff. If you have a mortgage, you’ll have to pay the balance at closing. But the equity you’ve built up in your home should ease the sting, especially if you’ve owned it for five years or more. Home equity loans and second mortgages also have to be paid off, and your lender may charge a fee to do so.

-- Commission. Typically 5% or 6% of the selling price, this amount will be split between your agent and the buyer’s. On a $300,000 selling price, a 5% commission comes out to $15,000. But commissions are totally negotiable.

-- Inspection. It’s smart to get an independent home inspection to find any major issues and get them fixed --before a potential buyer’s inspector finds them and uses them as bargaining tools. Figure on spending $500-$700.

-- Closing costs. Yes, sellers have closing costs. And depending on how strong or slow the market is, the buyers may demand that you also pay some, or all, of theirs. Under this broad heading, there are recording fees, title insurance, warranty, settlement fees, appraisal fees, lawyers’ charges and settlement agent’s fees, along with bills for property taxes, utilities and homeowner’s association dues for the months you lived in the house. Together, these could add up to as much as 10% of the selling price.

-- Repairs. There’s no way to estimate this in advance, but anything your buyer wants fixed means money out of your pocket. Big-ticket items like termite remediation or roof repairs are obviously expensive, but even minor fixes can add up.

-- Moving. You can save beaucoup bucks by “hiring” friends and family help you move (a few six-packs and a couple pizzas should do the trick). Ditto if you rent a van. If you employ professional movers, expect to pay a couple of thousand, easily -- more, if you’re moving across state lines.

-- Utilities. Many power and water companies require new customers to put up a deposit when they open accounts, especially if you are moving to another city or state. You’ll get it back when you move out. But for right now, it’s cash out of your pocket.

-- Travel. Cross this item out if you aren’t moving far. But if you are moving long-distance, figure on racking up some significant dollars for hotels and meals.

Homebuyers who expect their newly built castles to be flawless masterpieces are only fooling themselves: The perfect, zero-defect house has yet to be built.

A house is a giant jigsaw puzzle. Not only does it come in as many as 10,000 pieces -- many of which don’t always fit as precisely as they should -- it is put together by dozens of human beings, sometimes working at cross purposes in harsh, if not extreme, weather conditions, almost always under a fast-approaching deadline.

So, yes, builders make mistakes -- sometimes big ones. Like the house Avex Homes built in the Tampa area that was too close to its neighbor. The county rules say no house should be within 10 feet of another, but Avex crews built one with a gap of less than 6 feet. The builder was required to lop 4 feet off the completed house.

This kind of major snafu is a rare occurrence, to be sure. Even structural defects in which one or more load-bearing elements could suffer a catastrophic failure are few and far between.

According to Paul Thomas, national risk manager at 2-10 Home Buyers Warranty, an average of only 1 percent of all new houses suffer a major structural defect over their first 10 years. Of course, that varies; geographic areas with water intrusion issues or expansive soils tend to have more problems.

Minor issues occur more frequently. About 5 percent of all homes, Thomas reports, experience drywall cracks from foundations settling or wood shrinkage.

Face it: Nails pop out from the drywall as a house settles, concrete is going to crack, doors may not close precisely, a floor tile might crack and a bathtub or sink might have a scratch or two. Annoying, yes, but easily repaired without too much hassle.

But every builder has a whopper of a story about a big mistake. A subcontractor misreads a blueprint, a building inspector fails to catch a major flaw, or a product is totally defective and irreparable. Builders won’t talk about these miscues on the record, lest their names become synonymous with shoddy construction, but they’ll share them anonymously.

Here are some of their taller tales:

-- A building inspector in Coeur d’Alene, Idaho, discovered that a house’s foundation had been poured 6 inches over the property line, largely because there was 4 feet of snow on the ground. The foundation had to be removed and redone. Fortunately, the mistake was discovered before construction got any further. Had the house been built in its entirety, the builder would have had to seek a variance from the city -- an iffy prospect at best.

-- A Maryland builder once left his blueprints at home, and instead of going back to retrieve them, he guessed on the site lines. He guessed wrong, by 2 feet, and had to start over in the right place.

-- In Columbia, South Carolina, a builder poured the concrete slab over the pipes before he called for a plumbing inspection. He had to break up the slab and start all over again. And he said he has recurring nightmares about building the wrong house on the wrong lot -- a mistake he hasn’t made, at least not yet, but that remains his worst nightmare.

-- That nightmare became a reality for a Seattle builder, who was able to persuade his buyer to switch lots. And a Dayton, Ohio, builder who built four houses on the wrong lots is still mired in a court battle while the four houses sit empty.

-- Then there’s the story of the builder who built the garage ordered by one buyer on the house next door. He solved his dilemma by giving the garage to the neighboring house’s buyer free of charge, and building another one on the right house. “There wasn’t anything else I could do,” he told me.

-- Many builders have horror stories about carpentry nails being driven into plumbing pipes. And once those nails start to work themselves loose, the result is often a slow leak, but sometimes a gusher of a flood.

-- A San Antonio builder recalls the time a carpenter put a window in the wrong place. Just before stopping for lunch, he marked the center of where the window should be. But when returned, he used the mark as a corner, throwing the opening off-center by 18 inches. Only when the house was finished was the error discovered: Four windows lined up perfectly, but the fifth one didn’t.

But not all miscues turn out badly. In Boston, for example, a crew put a gable roof on a house that called for a Tudor style. The buyer was the first to notice the mistake; the builder, who thought it looked awful, was sick about it. He said he would remove the roof and replace it with the proper one.

But the buyer liked it just the way it was. So did some others: Of the next four buyers of the same model house, two ordered their homes with gable roofs as well.