The reduced inventory of unsold homes is key, says Mark Fleming, chief economist at CoreLogic, a housing data-analysis firm. For the past couple of years, house prices have risen in the spring and then slumped; the declining supply of houses for sale is reason to believe that won’t happen again this year, he says.

Builders began work on 26% more single-family homes in May 2012 than the depressed levels of May 2011. The stock of unsold newly built homes is back to 2005 levels. In each of the past four quarters, housing construction has added to economic growth. In the first quarter, it accounted for 0.4 percentage points of the meager 1.9% growth rate.

“Even with the overall economy slowing,” Wells Fargo Securities economists said, cautiously, in a note to clients, “the budding recovery in the housing market appears to be gradually gaining momentum.”