The housing market is the hottest it's been since right before the 2008 crash

• Home price growth and construction are the hottest they've been since 2006 - the peak of a housing bubble.
• Despite the similarities of some housing data from 15 years ago to today, experts see two very different markets.
• Conditions driving this market boom are "fundamentally, radically different," an economist told Insider.

Housing data is hitting levels unseen since 2006 in at least three different ways, begging the question of whether this is another bubble. Experts say this isn't that - it's economics.

Another housing bubble 15 years after the last one would be very bad news, as the epic pop of that market in 2008 threatened the stability of the entire global financial system. But while today's price inflation is similar to then, the drivers behind this market rally look different.

Nationwide home prices grew 12% year-over-year - their fastest pace since 2006 - this past February, according to the S&P CoreLogic Case-Shiller Index. Gains were broad-based, with all 20 cities tracked by the index experiencing price growth above their respective median levels.

Separately, CoreLogic's own home-price index also recorded the highest annual leap since 2006 in February. That gauge tracks home prices across the country, while S&P's index measures prices in 20 metropolitan areas.

Also, for the first time since 2005, the median sale price for previously owned single-family homes is higher than that for new construction. In other words, the premium Americans typically pay to be the first to live in a new house has been completely erased as homebuyers have rushed to buy any home on the market.

"The conditions underlying what happened way back then, during the bubble of '05 and '06, and what's driving price growth today are just fundamentally, radically different," Frank Nothaft, chief economist for CoreLogic, told Insider.

Where dubious lending and market euphoria powered the mid-2000s surge, today's boom is almost entirely due to a nationwide supply shortage. The monthly supply of homes sits near record lows of about 3 months, leading sellers to demand increasingly large sums for their properties. That compares to more than 12 months of supply in 2009.

Today's market is also backed by a strong underwriting process and isn't engulfed in a subprime mortgage crisis, Nothaft explained. The price growth we are currently experiencing, he continued, "is rooted in economics."

Record low mortgage rates and the heightened focus on space have sent buyer demand through the roof, but a pullback from prospective sellers and a lack of newbuilds have resulted in a national decline in homes for sale.

"When you put all these pieces together, increase in demand and limited supply, it pushes prices up and that's what we're seeing in the marketplace," Nothaft added.

Learning from post-crisis mistakes

Other gauges aren't just at their hottest levels since 2006, but their hottest levels full-stop. The median selling price for existing homes touched a record high of $329,100 in March, according to the National Association of Realtors. And though the supply of previously owned homes has edged higher in recent months, it's still close to February's all-time low of 1.03 million units.

"We've been underbuilding for years," Gay Cororaton, director of housing and commercial research for the National Association of Realtors (NAR), told Insider.

The shortage can be traced back to that 2008 housing crash and its long-term fallout. The buying frenzy seen throughout the 2000s had fueled a boom in new construction as builders rushed to meet unprecedented demand. But once the bubble burst, contractors pulled back on building in an effort to prop up demand. Construction rebounded slowly through the last decade, leaving the market with diminished inventories once the pandemic-era boom began.

Daryl Fairweather, chief economist at Redfin, told Insider that the last decade saw a massive drop-off in homebuilding. Fewer homes were built by a factor of 20 going all the way back to the 1960s, she said.

But the latest data suggests contractors are finally heeding the market's call. Home starts leaped nearly 20% last month to the highest level since, you guessed it, 2006. The reading also marks the largest month-over-month increase since 1990, underscoring the urgency faced by homebuilders.

Americans also seem prepared to keep the market boom alive for at least a while longer. The share of consumers planning to buy a home in the next six months rose to 8.9% in April from 8.1%, according to The Conference Board's Consumer Confidence Index. That's the highest proportion since 1987.

With millennials reaching peak homebuying age, supply bouncing back, and mortgage rates expected to move up slightly, economists don't expect the housing rally to pop, but instead settle into more sustainable growth.

"I think we will return more to the trend that we were seeing pre-pandemic," Nothaft said, which showed steady national price growth in the single digits. In February 2020, home prices increased by 4.1% year-over-year.

For millennials, who are entering or at peak homebuying age, that would represent a return to a pre-pandemic dynamic of record low mortgage rates but a housing market that still felt out of reach. It may not be a bubble, but it isn't exactly attainable, either.