Valley home prices soared in 2018. Here’s what you can expect this year.

Once upon a time, rising prices encouraged some home dwellers to sell their houses. More potential profit meant more homes coming on the market.

But for 51 straight months dating to autumn 2014, the supply of existing homes in Ada County has fallen in comparison with the same month a year earlier. This is so despite a rocket-propelled rise in prices. For 2018, Ada County’s overall median sales price was $314,000, the Boise Regional Realtors reported Monday. In 2017, it was $265,990. That’s an 18 percent gain.

Would-be sellers are standing pat even though the Realtors keep saying it’s a sellers market, particularly for the increasingly scarce homes at the low end of the price range. (The low end itself has been rising, too. Just try to find a conventional house for less than $200,000.)

A chart provided by Boise Regional Realtors shows that only one price category of used Ada County homes — those $1 million or more — has an inventory that favors buyers. That category has a housing supply to last for more than 16 months.

Provided by Boise Regional Realtors

New home sales rose 22.4 percent last year in Ada County. Used-home sales fell 4.1 percent.

“That doesn’t surprise me at all,” said Rick Gehrke, an agent with RE/Max Executives in Nampa who sells in both Ada and Canyon counties.

In December, there were 498 existing homes for sale, compared with 537 in December 2017, according to the Intermountain Multiple Listing Service. Overall, 7,933 used homes were sold in 2018, compared with 8,269 a year earlier.

The lack of used housing has led contractors to build more new homes and for buyers to consider buying new. In 2018, 3,148 new homes were sold, up from 2,571 in 2017. In 2017, new home sales were up 9.8 percent from 2016.

In December, the inventory of used homes wasn’t enough to supply a single month’s worth of sales, while the new home inventory had enough to last four months. Typically, a balanced market, one that doesn’t favor buyers or sellers, has four to six months of supply, Realtors say.

Existing homes priced between $700,000 and $999,000 have nearly a three-month inventory, but the seven categories below that all have less than a two-month inventory.

Among new houses, those between $250,000 and $399,999 have an inventory of more than four months, a balanced market. The only segment that favors buyers is between $700,000 and $999,999, with an inventory of more than seven months.

Agents cannot close sales if they lack homes to sell, as this chart shows:

Provided by Boise Regional Realtors

But the more things change, the more they stay the same. Gehrke said he expects demand to remain high in 2019 and for sales prices to be similar to last year.

“I don’t see any of the conditions that brought those prices to change,” he said. “People are continuing to move here from states like California where homes are worth more. Interest rates have fluctuated somewhat, but not enough to make a significant difference.”

In Canyon County, the median price for 2018 was $216,900, up 20.5 percent from $180,000 the year before. A total of 4,873 homes were sold during the year, up 302 from 2017.

In December, there were 282 used homes for sale, down 21 from December 2017. The number of available new homes was 326, down from 392 in 2017.

Reporter John Sowell has worked for the Statesman since 2013. He covers business and growth issues. He grew up in Emmett and graduated from the University of Oregon.If you like seeing stories like this, please consider supporting our work with a digital subscription to the Idaho Statesman.