The housing market is no stranger to supply constraints.

A toxic combination of wildly inflated lumber prices, a lack of new and existing homes, and the sheer number of borrowers willing to pay tens of thousands of dollars over ask on homes they’ve never seen in person, has created a pandemic-driven problem that the industry can’t quite shake.

But according to Doug Duncan, chief economist at Fannie Mae, it’s not going to be just one of these factors that brings the market back to some semblance of normalcy. It’s going to take all of them.

In an economic outlook panel at HousingWire’s Engage.marketing event on Thursday, Duncan explained that in the 2007 to 2009 downturn, the industry went from building 2.2 million units to 600,000, and stayed around that level for three years. In doing so, he noted, three-quarters of the supply chain simply wasn’t produced.

“It doesn’t just reappear,” Duncan said.