Residential activity was slower than expected in 2014, increasing by only 4%, according to the U.S. Census Bureau. Single-family home construction rose 12%, with total annual housing starts exceeding 1 million units, according to Dodge Analytics; an upward trend toward the U.S. peak of 2 million starts in 2006.

Multifamily units jumped 34%, becoming one of the industry’s leading growth segments. Economists expect multifamily construction to remain strong for the foreseeable future, considering the financial hurdles such as unemployment, credit conditions, and high student loans that are delaying millennials from buying homes.

Residential construction growth varies by region, with the “interior U.S.” leading the housing recovery due to lower overbuilding and strong agriculture and energy-based economies, according to Sullivan of the PCA.

“Des Moines has been strong for three years,” says Tim Janssen, vice president of Central Iowa Ready Mix, based in Des Moines. “We are about the size [we were] before the collapse in 2008.”