Wouldn't it be wonderful if the first house you bought was the last one you ever needed to own?

Imagine if the house lasted your entire lifetime -- that you'd never have to leave, uprooting your family in the process, and that you could even pass the place down to your descendants.

In other words, a forever home: one you could expand as the need for more space arose. One that could accommodate children, when they came along; your parents, when they became too old to live on their own; or an adult child returning to the nest. Maybe it could hold your parents and your kids at the same time.

Few people ever live in such a place. According to Redfin, people move from one house to another every dozen years or so. But that doesn't mean you can't do it. Indeed, anyone can.

With a little forethought and effort, you can build or buy a house for the ages. And it need not be an expensive, architect-designed custom house, either; production houses can fit the bill.

Practically any builder can construct such a house, "as long as they offer the appropriate set of upgrades," says Boyce Thompson, author of the new book "The Forever Home: Designing Houses to Last a Lifetime."

Unfortunately, most production builders tend to build for specific markets -- first-timers, for example, or trade-up buyers or empty nesters. But in doing so, Thompson says, "they give short shrift" to things buyers may require down the road.

Thompson is an excellent source on the subject. For 17 years, he was the editorial director of Builder, an award-winning trade publication serving the new-home business. (I once wrote occasional stories for Builder.) He's also the founding editor of six trade magazines, including Residential Architect, Big Builder and Digital Home.

"The Forever Home" is his fourth book, and features interviews with 20 families who have built their "immortal houses." It covers the topic from numerous perspectives, profiling young families, baby boomers, single parents, recently divorced people and more. It's full of big color photographs and even includes floor plans.

I asked Thompson, who concedes that he and his wife still live in an "obsolete" house in Bethesda, Maryland, about the factors to consider in a forever house. As you might have guessed, longevity is an important one.

"Think about what you may need for the long run," he advised. One-floor living is ideal, as are wider doorways, but most people automatically think of those things. But what about wider halls as well? Not only do you need them to accommodate a wheelchair, Thompson said, but they are also "more elegant."

A cradle-to-grave house should have a low- or no-threshold entry and a room on the first floor that can be turned into a bedroom if needed. A powder room that can be turned into a full bathroom is another must. Thompson suggests a half-wall between the sink and commode that can be removed to make way for a wheelchair, or you can make sure the powder room is next to a closet or pantry that can be converted into a roll-in shower -- one equipped with French drains to make it easier to access.

"Clearances around the toilet are big," said Thompson.

Don't forget the outside of the house, though, especially roofing, siding and windows. "These three are worth upgrading because they improve your home's energy and maintenance performance in the long run," he said.

It's probably cost-prohibitive to opt for the longest-lasting natural materials, like real stone and slate roofs. But fiber cement or cedar siding and faux-tile roofing will "last a long time with minimum maintenance," he said.

Speaking of costs, Thompson said a forever house "doesn't have to be more expensive," provided you do your research and plan ahead.

Some of his suggestions: Finish the basement when you need more space. Opt for a decent, functional kitchen instead of one that looks like the set for a cooking show. Hold back on fancy interior touches like crown molding until you have some extra cash. Plan for later additions.

In other words, "Only build what you need in the beginning, but plan for later," Thompson said.

New York architect Nathan Dalesio took that "enlightened path" when designing a house for his family, Thompson said, by first focusing on the basics: an airtight building with a resilient roof and durable windows. But Thompson said Dalesio's "most inspired move was to visualize future expansion."

"We planned the house so that we could add things down the road that were out of reach of our budget right now," said Dalesio.

Every homeowner pays property taxes. At least, they should. But sometimes, people can't -- or won't -- pay the piper, and the tax collector comes calling.

Local taxing authorities can take your house and sell it to obtain their due. But if the house fetches more than what you owe, the Supreme Court has now ruled that the authorities can't keep the difference.

That's contrary to the rules in more than 20 states, which allow what the nonprofit Pacific Legal Foundation calls "home equity theft." A dozen states, and the District of Columbia, allow tax collectors to keep everything they can get for your place, even if you owed far less, and nine others permit it under certain circumstances.

But in a rare unanimous ruling, the nation's top court has put the kibosh on the practice. "The taxpayer must render unto Caesar what is Caesar's, but no more," wrote Chief Justice John Roberts in his opinion on Tyler v. Hennepin County, noting that the practice violates the takings clause of the Fifth Amendment.

Now, warns PLF's Jim Manley, if the offending jurisdictions don't change their laws, "they could face damages in the millions in future lawsuits."

The National Association of Home Builders and the National Association of Realtors both filed amicus briefs for the case, and both celebrated the decision.

"No longer can localities seize windfalls on the excess proceeds from tax sales," said the NAHB in a statement on its website.

PLF, which has been fighting equity theft for years, brought the case to the high court on behalf of 94-year-old Geraldine Tyler, who owned a small one-bedroom apartment in Hennepin County, Minnesota. After moving to an assisted living facility, she fell behind on her property taxes to the tune of $2,300 -- plus $12,700 in penalties.

The tax collector pounced: The county seized the apartment, sold it for $40,000 and kept every dollar -- a difference of $25,000, give or take. Pure gravy for the county.

But the Supreme Court ruled that when the government takes someone's home equity to satisfy a property tax debt, it violates the takings clause, which bars the government from snatching private property without providing just compensation.

Writing for the 9-0 decision, Roberts said, "A taxpayer who loses her $40,000 house to the state to fulfill a $15,000 tax debt has made a far greater contribution to the public fisc than she owed."

And in a concurring opinion, Justice Neil Gorsuch, joined by Justice Ketanji Brown Jackson, wrote that the practice may also violate the Constitution's excessive fines clause, which limits the amount governments can take as punishment.

"Economic penalties imposed to deter willful noncompliance with the law are fines by any other name," Gorsuch wrote. "And the Constitution has something to say about them: They cannot be excessive."

In its ruling, the court rejected the county's argument that since Tyler had not paid her property taxes, she had effectively abandoned her apartment and had no right to the excess proceeds. But Roberts wrote that the county cannot frame her failure to pay as abandonment.

PLF attorney Christina Martin hailed the decision as "a major victory for property rights."

"This decision affirms that property rights are fundamental and don't depend solely on state law," said Martin, who argued Tyler's case pro bono. "The court's ruling makes clear that home equity theft is not only unjust, but unconstitutional."

Tyler's case will now go back to a trial court, where Martin will argue that she is owed the fair market value of her condo, minus her debt, as just compensation.

Meanwhile, PLF's battle to end home equity theft is moving to state legislatures, which have been put on notice to change their practices or face liability in future lawsuits. The nonprofit has even provided guidelines and model policies to help states reform their laws.

The 12 states identified by PLF that currently allow the practice (along with Washington, D.C.) are Alabama, Arizona, Colorado, Illinois, Maine, Massachusetts, Minnesota, Nebraska, New Jersey, New York, Oregon and South Dakota. The nine that allow it in limited circumstances are Alaska, California, Idaho, Montana, Nevada, Ohio, Rhode Island, Texas and Wisconsin.

Recently, North Dakota saw the light, changing its law to ban equity theft. Montana and Wisconsin have outlawed most such takings, but still have loopholes, PLF says.

In its brief, NAHB argued that state law cannot be used to circumvent traditional property interests. Both English and American common law require governments to return any surplus -- so-called remainder equity -- from property taken to pay debts, said Zach Packard, NAHB staff counsel.

In its own brief, NAR agreed: "Permitting the government to erase these vested property rights by the stroke of a pen undermines a core premise of property ownership."

If you brought a wad of cash with you from the sale of your old house, chances are pretty good you overpaid for your new place.

By how much? That's anyone's guess. But a new study published by UCLA's Anderson School of Management sheds some light.

Per a writeup on the university's website, the study found that "sellers who had collected large equity gains on their previous home overpaid by about 2% on average for their first subsequent home purchases." That might not sound like much, but it adds up: That 2% would equal $6,000 on a $300,000 house, for example.

Moreover, "the overpayments rose with the size of the windfalls, by an average (of) 7.9 cents for every dollar in equity gain the buyer had collected."

Not only do local buyers with fat wallets overspend, but they also drive up prices for everyone else, the study says.

That last part doesn't quite square with the popular wisdom that cash-heavy buyers, moving from high-cost markets to less-expensive places, are responsible for making houses more expensive for other buyers. That does happen, but the UCLA research found that equity-rich local movers drive up neighborhood prices by even more than out-of-towners.

Both fat-cat local buyers and their outlander cousins "voluntarily" overpay, the study found, because they don't verify the actual market values of their next homes before buying them. That information is readily available, but they don't take advantage of it.

"It looks as if they don't put in as much time and effort to get the right valuation," says assistant professor of finance Gregor Schubert, one of the study's three co-authors.

On the other hand, buyers who brought less equity to the deal -- the report didn't offer a cutoff point between "lots" of equity and "less" -- were the least likely to significantly overpay. And local buyers who lived in their old homes for longer periods (again, no definition given for "longer") were unlikely to overpay, probably because they were more attuned to local market conditions.

Nevertheless, the study puts a big dent in the thesis that people who move from, say, high-priced New York to a smaller, cheaper market are responsible for making housing more costly for everyone. Such transplants are even blamed for driving locals out of the market entirely.

They do pay more than necessary, the study said, but locals who made a bundle not only do the same, but the impact of locals overpaying lasts for six months before the market catches up.

The study covered some 3.1 million sales between 1996 and 2021 in which the seller bought another residence within nine months. On average, sellers moved from a place they'd lived for 6 1/2 years and collected a gain-on-sale of $86,244.

Though some sellers moved down the housing ladder, most bought larger, more expensive houses with more bells and whistles -- especially if they made out like bandits from their previous home's sale. Many of them seemed to use that newfound wealth as a substitute for doing the research about their next place.

"They choose to overpay and remain ignorant about the price rather than pay the effort costs necessary to become informed," the study said, noting that the impact extends to nearby properties. "Households with large equity gains that move into an area drive up their new neighbors' home prices by approximately the same amounts that they overpaid."

The lesson, obviously, is to do your homework, especially if you'd like to bank more of your equity. For starters, it's a good idea to work with a local agent who specializes in the particular neighborhoods where you want to live. Many agents practice exclusively in a particular community.

Absent that, look for the agent who books the most sales in your market. Generally, those who sell the most houses are the ones working the market day in and day out (backed by a supporting team of folks who handle the paperwork).

You should be presented with information on comparables: recently sold houses that are similar to the ones you are considering. Compare their prices to that of the place you want, but also pay attention to the trend line -- are prices moving up, going down or remaining steady? And look at asking prices for similar places that are still on the market -- again with a trend line.

In all cases, make sure your agent uses the most up-to-date figures. That will mean some work on the agent's part -- most published statistics are months old, and markets can turn on a dime -- but a good one will have gone the extra mile before you even ask.